On one occasion, the Eleventh Doctor recalled memories of his fourth incarnation meeting up with the command crew of the USS Enterprise, including McCoy, to combat a Cyberman invasion of Aprilia III. (COMIC: Assimilation²)
Behind the scenes
The mention of Dr McCoy in The Gallifrey Chronicles treats him as a fictional character (as do, implicitly, other references to Star Trek and Star Trek: The Next Generation in Doctor Who stories). Assimilation², of course, treats him as a "real" individual. Reconciling these diegetic levels is an exercise best left to the reader.
Assimilation² depicts McCoy with the likeness of actor DeForest Kelley, who originally portrayed him in Star Trek.
- Leonard McCoy at Memory Alpha, the Star Trek canon wiki
- Leonard McCoy at Memory Beta, the wiki that covers all licensed Star Trek works