10 Best Doctor Who Crossovers Ever

10. Star Trek: The Next Generation/Doctor Who: Assimilation²

In this eight-issue miniseries, the 11th Doctor, Amy, and Rory encounter the crew of the USS Starship Enterprise-D! The crossover takes place between the Star Trek: The Next Generation episodes "The Outcast" and "Cause and Effect."

When the Doctor lands the TARDIS on the ship's holodeck, a Federation planet was under attack from the Borg and the Cybermen's combined forces. As soon as the Doctor crossed over into the Star Trek universe, he finds that he's suddenly inundated with memories linking the 4th Doctor to a previous adventure with Captain Kirk as they battled an earlier generation of Cybermen.

The Doctor and Captain Jean-Luc Picard meet one another and soon discover the alliance between two of their most ruthless enemies. It isn't long before they agree to work together to defeat the alliance, but the Cybermen have other plans.

Almost immediately, the Cybermen unsurprisingly turn on the Borg, which sends them to Picard for help, which he reluctantly agrees to provide. The Enterprise outfits its weapons with gold since the Cybermen are susceptible to it. At the same time, the Doctor travels to the past to gather a vital piece of Borg technology. Together, the Doctor and Picard manage to defeat the Cybermen.