Larry Trask followed in his father's footsteps when he created the Sentinels Mark II, unaware of his own mutant gift for precognition at the time. Larry's upgrades made the Mark II among the most effective Sentinels to date, introducing their now infamous ability to adapt to new foes and obstacles, so that the Sentinels could never be beaten the same way twice. Instead of a Master Mold, these Sentinels were led by a Number 2.
After their initial debut in X-Men (1st series) #56-59, the Sentinels were tricked into flying into the sun, their logic identifying it as the source of human mutation and in need of disposal. These Sentinels resurfaced in the pages of Avengers, Marvel Super-Heroes, and Wolverine over the years.
