The New Mutants were a group of mutants united by Charles Xavier (a.k.a. Professor X) to take the place of the X-Men when he thought they died. Even with the return of the X-Men, Professor X still teached the new group for long time.
When he went to space, Magneto (a.k.a. Eric Magnus Lehnsherr) took his place for some months, and then, Cable. Finnally, with the X-tinction Agenda, the New Mutants were dissolved and X-Force was created. The last New Mutants were formed by Cannonball (Samuel Guthrie), Sunspot (Roberto da Costa), Wolfsbane (Rahne Sinclair), Mirage (Danielle Moonstar), Warlock (Son of Magus), Boomer (Tabitha), Skids (Skids Blevins), Rictor & Rusty (Rusty Collins)