Collocations for thinker - noun

brilliant, great
Einstein was one of the world's greatest thinkers.

influential, leading
deep, profound, serious
big (esp. AmE)
clear, logical
quick
creative, original
critical, free, independent
contemporary, modern
19th-century, classical, medieval, etc.
strategic
political, religious, scientific, etc.
conservative, liberal, radical, etc.
Christian, feminist, western, etc.

thinker on
a leading thinker on constitutional law