Circles

Circles are bad for representing numbers as their area doubles with only a $\sqrt{2}$ increase of the radius:

Image Source: NZZ Neue Zürcher Zeitung

Image Source: Al Gore/TED 12:15

Incidentally, this is the reason why you should refrain from using pie charts in most scenarios.

Axes

Image Source: reddit.com/r/dataisbeautiful

Other things terribly visualised

For more terrible data visualisations, see WTF Visualisations