Mike The Monkey

Mike is the pet of guitarist of the gorillaz. Noodle

Appearance

 * "5/4" (storyboard)
 * "DARE"
 * "Dirty Harry"
 * Roadkill: The Mixtape by Russel Hobbs - On the cover of the tape.
 * PAC-MAN - In the office window behind Russel

Now
According to Noodle during the August 6, 2020, reddit AMA, Mike is a "free monkey" that returned from a "portal".