10 Surprisingly Good Licensed Comic Books
2. Wildcats/Aliens
While most of the crossovers mentioned here happen outside of mainstream continuity, primarily for legal reasons, there is one notable exception.
The Wildcats/Aliens crossover is even now audacious and shocking. It would have repercussions for one of WildStorm's oldest ongoing titles and set up the genuinely game-changing comic The Authority.
Warren Ellis had been writing Stormwatch for several years and slowly laid the foundations for what would become The Authority. The only problem was to transition from one title to the other he would need to take the United Nations-backed superhero team off the board. When publisher Jim Lee asked him to write a Wildcats/Aliens crossover, he saw an opportunity to kill two birds with one stone.
Communication with Stormwatch's satellite headquarters is lost after the team encounters a strange alien rock. The Wildcats investigate only to discover that most members of Stormwatch are dead after a Xenomorph infestation. The remnants of Stormwatch and the Wildcats engage in a life or death battle to stop the xenomorphs from reaching the earth.