doer

Etymology

From Middle English doer, doar, doere, from Old English dōere (“a doer; worker”), equivalent to do + -er.

noun

1. Someone who does, performs, or executes; an active person, an agent.
   The doer and the thinker No allowance for the other. 1972, “Thick As A Brick”, Ian Anderson (lyrics), performed by Jethro Tull
   Though his name was closely linked to that of Physiocrats, he was less an armchair intellectual like Quesnay or the elder Mirabeau than a doer in the vein of Bertin and Trudaine …. 2002, Colin Jones, The Great Nation, Penguin, published 2003, page 295
   In schools, submission, not curiosity, was a highly valued virtue. Thinkers were out, doers were in. 25 Mar 2008, Aleksandra Lojek-Magdziarz, The Guardian