Agent O, is an owl that works for the O.W.C.A.; it is brown in color. Its first name is unknown, not much is shown of it but it was seen in "Traffic Cam Caper". It was injured, along with Agent D by Dennis the Bunny (a rouge agent) and had its left foot in a cast ("No More Bunny Business"). In "Phineas and Ferb Save Summer", it is instructed to find out "Who's who?"
It has large eyes with keen vision. It has Silent flight, perfect for stealth missions. It prefers night missions; it often naps during daytime hours. And it is an enthusiastic dancer.