Mantax is one of the primary antagonists of Super Smash Bros. Crossover. He is an Barraki being amongst the warlords of League Of Six Kingdoms who join forces with The Covenant into searching the Chaos Emeralds after escaping the Cosmic Chamber.
Reflecting 95,000 years ago he along with the League Of Six Kingdoms were assigned to protect the Matorans alongside Teridax and his League Of Six Kingdoms. However Mantax and the League became very curious and greedy about the Chaos Emeralds believing it would make them the strongest beings in the universe. He along with Pridak and his League put their hands on the Chaos Emeralds without caution and resulted him into being mutated into an vicious Barraki. He along with the League began invading and conquering many planets but were easily defeated by Teridax and were about to be destroyed by the Makuta's use of Chaos Emeralds on them. Mata Nui and Ur-Didact stopped Teridax and imprisoned the League Of Six Kingdoms into the Cosmic Chamber. He along with the League trained the Nocturnus Clan into developing high technology and eventually escaped the Chamber after blasting the walls with their newly created Squid Launcher. After escaping the League discovers that they were imprisoned in the Cosmic Chamber for 4000 years with the Emeralds now hidden. Suddenly they encounter an alien organization known as The Covenant whom are also searching for the Chaos Emeralds, however the League decides to join forces with them and begin invading Mushroom Kingdom. He debuts as one of the main antagonists in Season 1 attacking the Bob-omb Buddies led by the general Commander Derrick in Bob-omb Battlefield along with Pridak, Takadox, and their leading Covenant army. They defeat and capture Mario, Luigi, and Wario having Derrick escape. As Bowser attempted to defeat them, he was unable to defeat the savage warriors and fled. Later as Tahu who leads the Toa Mata helps Master Chief, Link, Kirby, and Yoshi board the Covenant ship Truth and Reconcilation, he alongisde Pridak and Takadox fight against the heroes with Yoshi defeating Takadox with the help of Toa of Water Gali. Suddenly however Mantax soon sneaks up on Yoshi and jumps on him easily frightening Yoshi and made Mantax burst out laughter towards him, this made Yoshi upset and took one of Mantax's Squid Launcher and blast at him, only to fuel anger towards the vicious Barraki grabbing Yoshi and tosses him out of the ship where Yoshi is caught by Goku. Mantax is defeated by Yoshi resulting in Pridak to attack Yoshi where Yoshi uses the Mario's cap becoming Mario and adapting his abilities and eventually defeat Pridak. However he along with Pridak and Takadox are angered by defeat and escape from the heroes alongside the Covenant to begin their next conquest to Dreamland.
Mantax is considered to be sneaky and secretive, always hiding and ambushing his opponents to attack