Not much is known about his history other than he is a Samoan. He was once friends with Cordelia Frost, Emma Frost's younger sister.
Mondo was created by Scott Lobdell and Chris Bachalo and first appeared in Generation X issue 3 (1995).
Major Story Arcs
The real deal?
To gain a position into Hellfire Club she handed Mondo over to the inner circle in her attempt to take the position of White Queen, but her scheme backfired and they kept Mondo but didn't give her a position. Cordelia went to her sister and told her, and Mondo was saved by Generation X and giving an invitation to join the school and accepted it. It was soon learned that the Mondo they saved wasn't really him but a plant based clone created by Black Tom Cassidy who had infiltrated the Hellfire Club and saved Mondo, he then took him under his wing and created the clone so that he could seek revenge on his cousin Banshee. Years ago, Black Tom had raised and used Banshee's daughter, Siryn, in his crimes. But when father and daughter met she mended her ways, and Tom always blamed Sean for taking her away and planned on taking his students away from him just as he did with Siryn.
The Mondo clone began to hunt down the other students while Emma Frost and Banshee fought Black Tom. He was about to attack and kill Jubilee when he was shot dead from behind by Bastion chief operative of Operation: Zero Tolerance.
Later the real Mondo was with Black Tom and Juggernaut. He was completely loyal to Black Tom and the real Mondo battled the members of Generation X. The team tried to turn him good but he laughed and said he had never met them before. Generation X and their teachers were able to defeat their opponents, but they still managed to escape. Mondo's current whereabouts are unknown.
Earth 295 - Age of apocalypse
In the Age of Apocalypse, Mondo was a heroic and kind member of this world's Generation neXt, which was led by Colossus and his wife Kitty Pryde. They were given the mission by Magneto to infiltrate the Core -a prison facility watched over by the Sugar Man- and rescue Colossus' sister Illyana Rasputin, who was crucial to Bishop's plan to save reality.
He was given the task to sneak into the compound through the ground and when he found her he let her stay in his stomach while he was in dirt form, but not for long in fear she would be digested. He was killed by Sugar-Man's razor sharp tongue even though he was in dirt form.
Able to absorb any organic or inorganic matter and take on the properties of anything he digested. Capable of transport through dirt.
Generation X TV/Movie
Mondo as portrayed by Bumper Robinson. He was a member of the generation X who fought the scientist who wants to gain psychic powers. He was mentored by Emma Frost and Banshee together with other Generation X members of Xavier's Institute. He is short-tempered and is easily attached to riots. He also displays the same powers that he have in the comic books. In the film, he is jokingly said to hate Jello because he fears he may accidentally absorb its consistency.
Mondo was among those students introduced to the those new recruits namely Jubilee and Skin. He treated them differently and dared him into a football game. He accidentally pulled Skin's arms stretching it. He was a close friend to Refrax and the two together with M became a hard challenge to be with. They have bullied Jubilee and Skin.
Mondo then started a riot with the humans after the team was granted a day outside the Institute. All of them was imprisoned but were able to come out with Emma's mental powers.
The team especially Mondo was scolded by Emma and was about to be expelled. But the team proclaimed that they are going to quit if he would be expelled.