He first appeared in Misc. Monday - Super Mario Bros! He was assigned to an agent (Codename Echo aka Al) and went on a hitman mission to defeat the terrorists of the world, which included dragons and lizards. The agency he worked for ran out of machines to rescue him after he fell through 942 kilometer holes in the ground and he died.
- When he died, his brain was put into the Mario Clone.
- He has a very high pitched voice.
- He has a daughter, wife, and son.
- Agent Mario was thought to be gay, as he stated early on in the mission that he wanted to suck Codename Echo's balls.
- He claims to have a swan that was killed by Dragon Terrorist Erincino.
- He seems to have a fear of suicide.
- He was originally hesitant to kill his first target before Al informed Agent Mario that his target killed his much beloved swan.
- Agent Mario never owned a swan.
- Agent Mario had a short cameo in Indie Sunday! Spark Rising while killing "Shy Guys" or as he reffered to them, ghosts.
- Agent Mario is also referenced in Indie Sunday! - Splasher, where the main character is looking for his swan.