Name a type of graph or chart

The rarest possible answer — almost no player finds it.

• Isotype chart— Otto Neurath's 1920s Vienna system that told statistics through repeated icons.
• Nightingale rose chart— Florence Nightingale used it to prove sanitation, not battle, killed soldiers.

Genuinely obscure. Most players never think of it.

• Bode plot
• Bullet graph— Designed by Stephen Few in 2005 to replace cluttered dashboard gauges.
• Bump chart
• Cartogram
• Chernoff faces— Cartoon faces whose eyebrows and noses encode the data.
• Chord diagram
• Combo chart
• Contour plot
• Control chart
• Dendrogram
• Density plot
• Dumbbell chart
• Eye chart— Snellen's letter pyramid squeaks in; it is literally called a chart.
• Forest plot
• Frequency polygon
• Hexbin plot
• Kagi chart
• Lollipop chart
• Lorenz curve
• Marimekko chart— Finnish textile prints inspired both the look and the name.
• Mosaic plot
• Ogive
• OHLC chart
• Parallel coordinates plot
• Point and figure chart
• QQ plot
• Renko chart
• Ridgeline plot— Nicknamed after Joy Division's Unknown Pleasures cover, itself real pulsar data.
• Slope chart— Edward Tufte pushed it for showing change between two points.
• Smith chart
• Sparkline
• Step chart
• Streamgraph— A 2008 New York Times box-office chart made it famous.
• Sunburst chart
• Surface plot
• Ternary plot
• Treemap
• Waffle chart
• Wind rose

Uncommon — only a minority of players land here.

• Bell curve
• Box plot
• Bubble chart
• Candlestick chart— Rice traders in 1700s Osaka were drawing these before Wall Street existed.
• Choropleth map— Greek for 'area' times 'multitude': regions shaded by a value.
• Dot plot
• Funnel chart
• Gantt chart— Popularized around 1910 by engineer Henry Gantt, who never patented it.
• Gauge chart
• Growth chart
• Network graph
• Organizational chart
• Pareto chart
• Pedigree chart
• PERT chart
• Population pyramid
• Radar chart
• Sankey diagram— Named for a 19th-century Irish captain who charted steam-engine energy waste.
• Stacked bar chart
• Stem-and-leaf plot
• Timeline
• Tree diagram
• Violin plot— A box plot with the full distribution's shape mirrored on both sides.

A solid, middling pick shared with plenty of other players.

• Area chart
• Doughnut chart
• Flowchart
• Heat map
• Histogram
• Mind map
• Pictograph
• Scatter plot
• Tally chart
• Venn diagram

An overthought pick that scores below the middle of the board.

• Waterfall chart— Consultants' favorite staircase for walking a total up and down.
• Word cloud— Bigger words just mean more mentions, whatever the slide implies.

The most common answer on the board.

• Bar chart
• Line graph
• Pie chart