Mitch, also known as Big Mitch, is an intergalactic criminal. Among his crimes are poaching various extraterrestrial creatures, imprisoning them aboard his clandestine space station, and attempting to seize absolute control over the galaxy. Deviously clever and highly elusive, Mitch has made himself known across the universe as a formidable threat. However, his plans are always brought to a halt by Meap, an experienced agent of an intergalactic security force, with the frequent assistance of humans Phineas, Ferb, Isabella, and Candace.
Heinz Doofenshmirtz painted a face on a balloon and sprayed it with a lifelong lasting spray when he was a kid. He named it Balloony. Though, one day while he was protecting the Doofenshmirtz family's garden while being a lawn gnome, Balloony floated away. Later, Mitch found Balloony floating in space, called him his best friend and named him "Colin".
During the Cutonium search
Mitch was in search for the cutonium, an alien element that makes its consumer cuter. Following the dormant trail of cuteness, the cutonium was discovered to be in Seattle. In pursuit of the cutonium, Mitch battles Meap, Phineas, Ferb, Candace and Isabella. However, Dr. Doofenshmirtz finds the cutonium first and drinks it, thinking it's coffee. Mitch then kidnaps Doofenshmirtz and takes him to his fortress on his home planet. He then extracts the cutonium from Doofenshmirtz and he drank it to make himself the "cutest thing that ever existed". He became so cute that he mesmerized the entire Meap army and Phineas, rendering them unable to attack him. Phineas returned to normal after seeing Isabella, since he considers her to be cuter than Mitch. Phineas tells Isabella that she is their "secret cute weapon" and sends her out to "out-cute" Mitch. Isabella confronts Mitch with a cute face and says to him "What'cha doin'?". Her cuteness was great enough to make Mitch collide with a wall, making the cutonium come out of him and freeing the Meap army from their trance ("Meapless in Seattle").
Mitch is apparently known as "Big Mitch" to his friends.
He dislikes being called a zookeeper because "that sort of legitimizes" his capture of other creatures.
The voice of Mitch is done by English comedy actor David Mitchell. The name Mitch is similar to his voice-actor's last name.
He only says the word "meap" without his universal mustache translator. This is also true of his nemesis Meap and the rest of the inhabitants of their home planet.
Balloony was the rarest "creature" he has in his spaceship.
Mitch is actually the same size as Meap, as he is seen outside of his suit in "Meapless in Seattle". Meap did not previously know that Mitch could step outside his suit. The specific reason for why he wears a suit is unknown.