Calvin the Cat

 is a cat, golden brown tabby with brown stripes, paler chest/belly, and green eyes. His first name is unknown, not much is shown of him but he was seen in "Traffic Cam Caper".

Mindless animal mode
In mindless animal mode, Agent K is sleeker and his eyes are bigger.

Owner


In "Interview With a Platypus", he was seen with an elderly lady with three other cats.

Background Information

 * There is a confusion on its codename:
 * Most of the agents are named after the kind of animal they are, but when more than one animal would have the same code name, exceptions are made. The chicken in this episode is specifically addressed as "Agent C", which leads to the cat being referred to as a kitty. However two agents from different divisions can share the same name as Pinky and Perry the Platypus are both Agent P.
 * Also shown in the episode is a kangaroo, but it is not specifically addressed, so it is not known by what agent code letter the kangaroo goes by. Since these characters are not shown in episodes a lot they are addressed as Agent K.
 * An Agent W has been addressed by codename, but later, another Agent W addressed by codename appears ("She's the Mayor").
 * He/she appears in "Phineas and Ferb The Movie: Across the 2nd Dimension", where he is noticeably thinner although this could just be due to it being his mindless animal mode.
 * Agent K, Perry and Pinky are the only agents that have owners to be seen.
 * His nemesis is Rodney.

Appearances

 * "Traffic Cam Caper
 * "Interview With a Platypus"
 * "Robot Rodeo"
 * "Phineas and Ferb The Movie: Across the 2nd Dimension"
 * "Agent Doof"