1) Academic 2) An important intellectual 3) Brain 4) British slang for the brain 5) Creative thinker 6) DC Comics supervillain 7) Golden Age supervillain 8) Intellect 9) Intellectual 10) Mind 11) One may be deep 12) Philosopher 13) Rodin sculpture with the 14) Scholar 15) Scholarly sort 16) She uses her head 1) Arranger 2) Brain 3) Brainworker 4) Classifier 5) Excogitator 6) Idea man 7) Imager 8) Muser 9) Organizer 10) Philosopher 11) Philosophiser 12) Philosophizer 13) Ponderer 14) Prophet 15) Ratiocinator 16) Reasoner 17) Ruminator 18) Sage 19) Solver 20) Speculator 21) Surmiser 22) Theorist 
• (n.) One who thinks; especially and chiefly, one who thinks in a particular manner; as, a close thinker; a deep thinker; a coherent thinker.
Think'er noun One who thinks; especially and chiefly, one who thinks in a particular manner; as, a close thinker ; a deep thinker ; a coherent thinker . 
Thinker is British slang for the brain.
[n] - someone who exercises the mind (usually in an effort to reach a decision)
creative thinker noun an important intellectual; `the great minds of the 17th century`