Sergei the Snail, also known as Agent S, is a snail agent working for the O.W.C.A.. It was briefly assigned to Heinz Doofenshmirtz when Doofenshmirtz was downgraded as a low threat villain ("Oh, There You Are, Perry"). It was assigned again to Doofenshmirtz when Perry became too famous to move without notice ("Perry The Actorpus").