Marvel: Fire/Heat Immunity

Alexander Summers (Havok)
Havok is virtually immune to the effects of most forms of heat.

Ben Hamill (Match)
Match is seemingly immune to fire and high temperatures. As a side-effect of his powers, thermal production causes his skin to glow with heat and constantly radiates flame from his scalp.

Roberto da Costa (Sunspot)
As is the norm with most pyrokinetics, Sunspot is immune to all forms of heat and fire as they simply add to his abilities, and his mutant metabolism is able to simply convert these two forms and augment his abilities. This includes heat powers that are directed at him as well as heat that is present because of weather conditions. Sunspot has also been seen with the ability to absorb the energy that fire gives off and has remained unharmed while walking through it.