Ultimonito was the mascot of Guerreros del Atlantida and the rudo rival of Monito. He was usual seen with either Ultimo Guerrero or Atlantis. There was a contest to come up with a better name for the monkey-like creature, but no name or winner was ever announced.
Ultimonito has never officially gone away, though he's faded away. Since Atomo started as a regular, Ultimomonito's only appeared with Ultimo & Atlantis and for important matches with the group. Atomo is a tecnico and Ultimonito was a rudo, and CMLL's not acknowledged they are the same person.
In April 2008, Mini Maximo debuts. He's apparently the unmasked Atomo, and is still wrestling as Atomo in some locales.
Returned to CMLL in 2010 as Mini Maximo. Also debuted as the mascot for Rey Bucanero as Perico a parro to go along with Bucanero's pirate theme.