Thinker could refer to:
The Thinker from Justice League Unlimited.
- Clifford DeVoe, A DC Comics supervillain and foe of the Golden Age Flash.
- Clifford DeVoe, Version seen in the DC Animated Universe.
- Clifford DeVoe, Version seen on the Batman: The Brave and the Bold animated series.
- Cliff Carmichael, A DC Comics supervillain and foe of Firestorm; Member of the Suicide Squad
- Desmond Connor, A DC Comics supervillain and foe of Batman.
- Thinker AI, A cybernetic entity featured in DC Comics titles.
- Mad Thinker, A Marvel Comics supervillain and foe of the Fantastic Four.
- Sarah II, The Thinker from the Ultimate Marvel Universe.