A burlesque tyrant in The Rehearsal, by G. Villiers, Duke of Buckingham (1672). He kills every one, “sparing neither friend nor foe.” The name stands for a blustering braggart, and the farce is said to have been a satire on Dryden's inflated tragedies. (See Bayes, Bobadil.)
“[He] frights his mistress, snubs up kings, baffles armies,and does what he will, without regard to numbers, good sense, or justice.” —Bayes: The Rehearsal.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Drawcansir from Infoplease: