The X-Men #8

The X-Men train in the Danger Room under Cyclops’ watch. Cyclops thinks to himself about how much he loves Jean. Cyclops doesn't feel like he can tell her, especially now he is the new leader of the X-men. Jean also has fallen for cyclops.While out on the town Beast saves a boy but is attacked by an angry mob. Due to the hate humans have towards mutants (including the X-Men who protect both mutants and humans) Beast leaves the X-Men. Cyclops contacts the Professor but is told not to worry about Beast. Professor X is inside a cave, in search for Lucifer. Later Beast joins a wrestling match and fights another mutant by the name of Unus the Untouchable. Unus wants to join the Brotherhood, but Mastermind tells Unus that Magneto must gain his trust after what happened with the Blob. To earn Magneto's trust. Unus must find the X-Men and defeat them. On the streets, Unus sees a bank being robbed and takes the money for himself. The X-Men spot Unus and fail to beat him due to his force-field. Beast returns to the school to make a weapon that increases Unus's power and then leaves. The X-Men go after him, not knowing his true intentions. The Beast uses the weapon on Unus and makes him completely untouchable. Unus can’t touch anything or even eat. Unus is about to going insane from hunger so Beast uses the ray gun to reverse the effects on Unus. Beast warns Unus that they will keep the Ray gun for use against Unus if he is to return to his devious ways. After the battle Beast rejoins the X-Men.

This is the first apearence of Unus, and the first time Professor says something about Lucifer.