Agent S is an O.W.C.A. agent who first appeared in "La Candace-Cabra".
Agent S was at the animal sensitivity seminar but soon left after Carl dismissed the agents. He and the other agents then growled at Monogram for saying humans are higher species. Later, in "Phineas and Ferb Save Summer", he participated in the first and second brawl with evil scientists. He attacked an unnamed scientist with green hair, who may have been her nemesis.
- According to the secret file, Agent S uses his tongue to taunt evil, he's great for securing potential flight risks, and has a tendecy to tie himself in knots when nervous