Callisto is the leader of the Morlocks.
Callisto organised the capture of Cyclops and Jean Grey as she wanted to make an heir with male X-Man. Callisto and the Morlocks were later attacked by the X-Men and the Morlock leader duelled with Storm for leadership of the group. Storm won but she handed leadership of the group back to Callisto while she was gone, when she failed in persuading the Morlocks to come with her to Xavier's Institute. Callisto and the other Morlocks were later captured by Lady Deathstrike and the Reavers but the X-Men later freed them. When Leech became seriously ill, Callsito sent for the X-Men to come and save the young Morlock. At this time, Storm handed full leadership of the Morlocks back to Callisto.
Alternate Reality Versions
Age of Apocalypse
Callisto is seen as part of the mutant rebellion.