Professor Parenthesis is the main antagonist of the Phineas and Ferb television episode "O.W.C.A. Files." He is an evil flea scientist bent on taking over O.W.C.A. with his own army of Mecha-Fleas to take control of all of O.W.C.A.'s agents to do his bidding for him. Unlike most evil-doers who are dealt with by the agents, he is clearly a more intelligent and dangerous villain, always putting on a few tricks up his sleeve.
He has a habit of mispronouncing words by putting emphasis on the wrong syllables.
In his usual human appearance, Parenthesis has tan skin, blue eyes, and light yellow hair pointing upon his forehead. His head resembles that of a round bracket, hence his name. He wears a white lab coat with two light-green shoulder pads, green shorts, and pink slippers.
However, this appearance was nothing more than an android to conceal his true appearance: that of a tiny blue four-armed flea wearing a white shirt and pink slippers. Parenthesis' android is also capable of procuring four mechanical tentacles as back-up weapons and a giant LCD screen to show his true face to his enemies.