diff --git a/client/src/components/categorical/value.js b/client/src/components/categorical/value.js
index 15c45d49..705412c9 100644
--- a/client/src/components/categorical/value.js
+++ b/client/src/components/categorical/value.js
@@ -13,23 +13,41 @@ import * as globals from "../../globals";
   world: state.world
 }))
 class CategoryValue extends React.Component {
-  toggleOff() {
+  toggleOff = () => {
     const { dispatch, metadataField, categoryIndex } = this.props;
     dispatch({
       type: "categorical metadata filter deselect",
       metadataField,
       categoryIndex
     });
-  }
+  };
 
-  toggleOn() {
+  toggleOn = () => {
     const { dispatch, metadataField, categoryIndex } = this.props;
     dispatch({
       type: "categorical metadata filter select",
       metadataField,
       categoryIndex
     });
-  }
+  };
+
+  handleMouseEnter = () => {
+    const { dispatch, metadataField, categoryIndex } = this.props;
+    dispatch({
+      type: "category value mouse hover start",
+      metadataField,
+      categoryIndex
+    });
+  };
+
+  handleMouseExit = () => {
+    const { dispatch, metadataField, categoryIndex } = this.props;
+    dispatch({
+      type: "category value mouse hover end",
+      metadataField,
+      categoryIndex
+    });
+  };
 
   render() {
     const {
@@ -79,6 +97,8 @@ class CategoryValue extends React.Component {
           justifyContent: "space-between"
         }}
         data-testclass="categorical-row"
+        onMouseEnter={this.handleMouseEnter}
+        onMouseLeave={this.handleMouseExit}
       >
         <div
           style={{
@@ -92,9 +112,7 @@ class CategoryValue extends React.Component {
         >
           <label className="bp3-control bp3-checkbox">
             <input
-              onChange={
-                selected ? this.toggleOff.bind(this) : this.toggleOn.bind(this)
-              }
+              onChange={selected ? this.toggleOff : this.toggleOn}
               data-testclass="categorical-value-select"
               data-testid={`categorical-value-select-${metadataField}-${displayString}`}
               checked={selected}
diff --git a/client/src/components/graph/graph.js b/client/src/components/graph/graph.js
index 63f89b1a..05106dc5 100644
--- a/client/src/components/graph/graph.js
+++ b/client/src/components/graph/graph.js
@@ -8,6 +8,8 @@ import memoize from "memoize-one";
 
 import * as globals from "../../globals";
 import setupSVGandBrushElements from "./setupSVGandBrush";
+import setupCentroidSVG from "./setupCentroidSVG";
+import actions from "../../actions";
 import _camera from "../../util/camera";
 import _drawPoints from "./drawPointsRegl";
 import scaleLinear from "../../util/scaleLinear";
@@ -22,7 +24,9 @@ import scaleLinear from "../../util/scaleLinear";
   selectionTool: state.graphSelection.tool,
   currentSelection: state.graphSelection.selection,
   layoutChoice: state.layoutChoice,
-  graphInteractionMode: state.controls.graphInteractionMode
+  centroidLabel: state.centroidLabel,
+  graphInteractionMode: state.controls.graphInteractionMode,
+  colorAccessor: state.colors.colorAccessor
 }))
 class Graph extends React.Component {
   computePointPositions = memoize((X, Y, scaleX, scaleY) => {
@@ -70,7 +74,8 @@ class Graph extends React.Component {
       sizes: null
     };
     this.state = {
-      svg: null,
+      toolSVG: null,
+      centroidSVG: null,
       tool: null,
       container: null
     };
@@ -139,9 +144,11 @@ class Graph extends React.Component {
       selectionTool,
       currentSelection,
       layoutChoice,
-      graphInteractionMode
+      graphInteractionMode,
+      colorAccessor,
+      centroidLabel
     } = this.props;
-    const { reglRender, regl, svg } = this.state;
+    const { reglRender, mode, regl, toolSVG, centroidSVG } = this.state;
     let stateChanges = {};
 
     if (reglRender) {
@@ -216,16 +223,10 @@ class Graph extends React.Component {
       );
     }
 
-    if (
-      prevProps.responsive.height !== responsive.height ||
-      prevProps.responsive.width !== responsive.width ||
-      /* first time */
-      (responsive.height && responsive.width && !svg) ||
-      selectionTool !== prevProps.selectionTool
-    ) {
+    const createToolSVG = () => {
       /* clear out whatever was on the div, even if nothing, but usually the brushes etc */
       d3.select("#graphAttachPoint")
-        .selectAll("svg")
+        .select("#tool")
         .remove();
 
       let handleStart;
@@ -241,16 +242,63 @@ class Graph extends React.Component {
         handleEnd = this.handleLassoEnd.bind(this);
         handleCancel = this.handleLassoCancel.bind(this);
       }
-      const { svg: newSvg, tool, container } = setupSVGandBrushElements(
+
+      const { svg: newToolSVG, tool, container } = setupSVGandBrushElements(
         selectionTool,
         handleStart,
         handleDrag,
         handleEnd,
         handleCancel,
         responsive,
-        this.graphPaddingRight
+        this.graphPaddingRight,
+        graphInteractionMode
       );
-      stateChanges = { ...stateChanges, svg: newSvg, tool, container };
+
+      stateChanges = { ...stateChanges, toolSVG: newToolSVG, tool, container };
+    };
+
+    const createCentroidSVG = () => {
+      d3.select("#graphAttachPoint")
+        .select("#centroid-container")
+        .remove();
+
+      if (centroidLabel.metadataField === "" || !centroidLabel.centroidXY) {
+        return;
+      }
+
+      const centroidScreen = this.mapPointToScreen(centroidLabel.centroidXY);
+
+      const newCentroidSVG = setupCentroidSVG(
+        responsive,
+        this.graphPaddingRight,
+        centroidScreen,
+        centroidLabel.categoryField,
+        colorAccessor
+      );
+
+      stateChanges = { ...stateChanges, centroidSVG: newCentroidSVG };
+    };
+
+    if (
+      prevProps.responsive.height !== responsive.height ||
+      prevProps.responsive.width !== responsive.width
+    ) {
+      // If the window size has changed we want to recreate all SVGs
+      createToolSVG();
+      createCentroidSVG();
+    } else if (
+      (responsive.height && responsive.width && !toolSVG) ||
+      selectionTool !== prevProps.selectionTool ||
+      prevProps.graphInteractionMode !== graphInteractionMode
+    ) {
+      // first time or change of selection tool6
+      createToolSVG();
+    } else if (
+      centroidLabel !== prevProps.centroidLabel ||
+      (responsive.height && responsive.width && !centroidSVG)
+    ) {
+      // First time for centroid or label change
+      createCentroidSVG();
     }
 
     /*
@@ -260,7 +308,7 @@ class Graph extends React.Component {
     if (
       currentSelection !== prevProps.currentSelection ||
       graphInteractionMode !== prevProps.graphInteractionMode ||
-      stateChanges.svg
+      stateChanges.toolSVG
     ) {
       const { tool, container } = this.state;
       this.selectionToolUpdate(
@@ -588,12 +636,7 @@ class Graph extends React.Component {
             right: 0
           }}
         >
-          <div
-            style={{
-              display: graphInteractionMode === "select" ? "inherit" : "none"
-            }}
-            id="graphAttachPoint"
-          />
+          <div id="graphAttachPoint" />
           <div style={{ padding: 0, margin: 0 }}>
             <canvas
               width={responsive.width - this.graphPaddingRight}
diff --git a/client/src/components/graph/setupCentroidSVG.js b/client/src/components/graph/setupCentroidSVG.js
new file mode 100644
index 00000000..68b7a253
--- /dev/null
+++ b/client/src/components/graph/setupCentroidSVG.js
@@ -0,0 +1,34 @@
+import * as d3 from "d3";
+import styles from "./graph.css";
+
+export default (responsive, graphPaddingRight, xy, text, colorBy) => {
+  const containerWidth = responsive.width - graphPaddingRight;
+
+  const svg = d3
+    .select("#graphAttachPoint")
+    .append("svg")
+    .attr("id", "centroid-container")
+    .attr("data-testid", "centroid-overlay")
+    .attr("width", containerWidth)
+    .attr("height", responsive.height)
+    .attr("class", `${styles.graphSVG}`)
+    .style("z-index", 998)
+    .style("pointer-events", "none");
+  //  TODO: Create own styles, ask Colin for an explanation on the css
+  // For now I'm going to put centroid z-index at 998 and lasso on 999
+
+  const label = svg
+    .append("g")
+    .attr("transform", `translate(${xy[0]}, ${xy[1]})`);
+
+  label
+    .append("text")
+    .attr("text-anchor", "middle")
+    .text(text)
+    .style("font-family", "Roboto Condensed")
+    .style("font-size", "18px")
+    .style("font-weight", "700")
+    .style("fill", colorBy ? "black" : "rgb(32, 178, 212)");
+
+  return svg;
+};
diff --git a/client/src/components/graph/setupSVGandBrush.js b/client/src/components/graph/setupSVGandBrush.js
index 7553bfe4..04e38e4f 100644
--- a/client/src/components/graph/setupSVGandBrush.js
+++ b/client/src/components/graph/setupSVGandBrush.js
@@ -16,15 +16,19 @@ export default (
   handleEndAction,
   handleCancelAction,
   responsive,
-  graphPaddingRight
+  graphPaddingRight,
+  graphInteractionMode
 ) => {
   const svg = d3
     .select("#graphAttachPoint")
     .append("svg")
+    .attr("id", "tool")
     .attr("data-testid", "layout-overlay")
     .attr("width", responsive.width - graphPaddingRight)
     .attr("height", responsive.height)
-    .attr("class", `${styles.graphSVG}`);
+    .attr("class", `${styles.graphSVG}`)
+    .style("z-index", 999)
+    .style("display", graphInteractionMode === "select" ? "inherit" : "none");
 
   if (selectionToolType === "brush") {
     const brush = d3
diff --git a/client/src/reducers/centroidLabel.js b/client/src/reducers/centroidLabel.js
new file mode 100644
index 00000000..5582e5cc
--- /dev/null
+++ b/client/src/reducers/centroidLabel.js
@@ -0,0 +1,44 @@
+import calcCentroid from "../util/centroid";
+
+const initialState = {
+  metadataField: "",
+  categoryIndex: -1,
+  categoryField: "",
+  centroidXY: [-1, -1]
+};
+
+const CentroidLabel = (state = initialState, action, sharedNextState) => {
+  const { categoricalSelection, world, layoutChoice } = sharedNextState;
+  const { metadataField, categoryIndex } = action;
+  const categoryField =
+    categoricalSelection?.[metadataField]?.categoryValues[categoryIndex];
+  switch (action.type) {
+    case "category value mouse hover start":
+      return {
+        ...state,
+        metadataField,
+        categoryIndex,
+        categoryField,
+        centroidXY: calcCentroid(
+          world,
+          metadataField,
+          categoryField,
+          layoutChoice.currentDimNames
+        )
+      };
+
+    case "category value mouse hover end":
+      if (
+        metadataField === state.metadataField &&
+        categoryIndex === state.categoryIndex
+      ) {
+        return initialState;
+      }
+      return state;
+
+    default:
+      return state;
+  }
+};
+
+export default CentroidLabel;
diff --git a/client/src/reducers/index.js b/client/src/reducers/index.js
index f223a9e9..96ea5c23 100644
--- a/client/src/reducers/index.js
+++ b/client/src/reducers/index.js
@@ -16,37 +16,39 @@ import layoutChoice from "./layoutChoice";
 import responsive from "./responsive";
 import controls from "./controls";
 import resetCache from "./resetCache";
+import centroidLabel from "./centroidLabel";
 
 import undoableConfig from "./undoableConfig";
 
 const Reducer = undoable(
-    cascadeReducers([
-        ["config", config],
-        ["universe", universe],
-        ["world", world],
-        ["layoutChoice", layoutChoice],
-        ["categoricalSelection", categoricalSelection],
-        ["continuousSelection", continuousSelection],
-        ["graphSelection", graphSelection],
-        ["crossfilter", crossfilter],
-        ["colors", colors],
-        ["controls", controls],
-        ["differential", differential],
-        ["responsive", responsive],
-        ["resetCache", resetCache]
-    ]),
-    [
-        "world",
-        "categoricalSelection",
-        "continuousSelection",
-        "graphSelection",
-        "crossfilter",
-        "colors",
-        "controls",
-        "differential",
-        "layoutChoice"
-    ],
-    undoableConfig
+  cascadeReducers([
+    ["config", config],
+    ["universe", universe],
+    ["world", world],
+    ["layoutChoice", layoutChoice],
+    ["categoricalSelection", categoricalSelection],
+    ["continuousSelection", continuousSelection],
+    ["graphSelection", graphSelection],
+    ["crossfilter", crossfilter],
+    ["colors", colors],
+    ["controls", controls],
+    ["differential", differential],
+    ["responsive", responsive],
+    ["centroidLabel", centroidLabel],
+    ["resetCache", resetCache]
+  ]),
+  [
+    "world",
+    "categoricalSelection",
+    "continuousSelection",
+    "graphSelection",
+    "crossfilter",
+    "colors",
+    "controls",
+    "differential",
+    "layoutChoice"
+  ],
+  undoableConfig
 );
 
 const store = createStore(Reducer, applyMiddleware(thunk));
diff --git a/client/src/reducers/undoableConfig.js b/client/src/reducers/undoableConfig.js
index a94d9c8e..76c59228 100644
--- a/client/src/reducers/undoableConfig.js
+++ b/client/src/reducers/undoableConfig.js
@@ -29,7 +29,10 @@ const skipOnActions = new Set([
   "clear all user defined genes",
 
   "get single gene expression for coloring started",
-  "get single gene expression for coloring error"
+  "get single gene expression for coloring error",
+
+  "category value mouse hover start",
+  "category value mouse hover end"
 ]);
 
 /*
diff --git a/client/src/util/centroid.js b/client/src/util/centroid.js
new file mode 100644
index 00000000..2cb1b60e
--- /dev/null
+++ b/client/src/util/centroid.js
@@ -0,0 +1,58 @@
+import quantile from "./quantile";
+
+/*
+  Centroid coordinate calculation
+*/
+const calcMeanCentroid = (world, annoName, annoValue, layoutDimNames) => {
+  const centroid = { x: 0, y: 0, size: 0 };
+  const annoArray = world.obsAnnotations.col(annoName).asArray();
+  const layoutXArray = world.obsLayout.col(layoutDimNames[0]).asArray();
+  const layoutYArray = world.obsLayout.col(layoutDimNames[1]).asArray();
+
+  for (let i = 0, len = annoArray.length; i < len; i += 1) {
+    if (annoArray[i] === annoValue) {
+      centroid.x += layoutXArray[i];
+      centroid.y += layoutYArray[i];
+      centroid.size += 1;
+    }
+  }
+
+  if (centroid[2] !== 0) {
+    centroid.x /= centroid.size;
+    centroid.y /= centroid.size;
+  }
+
+  return [centroid.x, centroid.y];
+};
+
+const calcMedianCentroid = (world, annoName, annoValue, layoutDimNames) => {
+  const centroidX = [];
+  const centroidY = [];
+  let hasFinite = false;
+
+  const annoArray = world.obsAnnotations.col(annoName).asArray();
+  const layoutXArray = world.obsLayout.col(layoutDimNames[0]).asArray();
+  const layoutYArray = world.obsLayout.col(layoutDimNames[1]).asArray();
+
+  for (let i = 0, len = annoArray.length; i < len; i += 1) {
+    if (annoArray[i] === annoValue) {
+      hasFinite =
+        Number.isFinite(layoutXArray[i]) || Number.isFinite(layoutYArray[i])
+          ? true
+          : hasFinite;
+      centroidX.push(layoutXArray[i]);
+      centroidY.push(layoutYArray[i]);
+    }
+  }
+
+  if (hasFinite) {
+    const medianX = quantile([0.5], Float64Array.from(centroidX));
+    const medianY = quantile([0.5], Float64Array.from(centroidY));
+
+    return [medianX, medianY];
+  }
+
+  return null;
+};
+
+export default calcMedianCentroid;