Following this post about crossovers between different settings, I thought I’d add a Whovian addendum.
The Whoniverse can swallow entire settings whole and solve their central conflicts in one story. These are generally somewhat parodic examples with the serial numbers filed off, for obvious reasons.
But now and then, a crossover on an equal footing could be played straight. Sticking within the rules of the visited setting will give a different feel to running roughshod over a recognisable parody.
RTD wanted the Doctor to meet a real Star Trek crew - Enterprise would have been the most practical. Of course, godlike alien tricksters are pretty common in Trek’s continuities. Would they have run with the Cybermen/Borg comparison, as the IDW comics did?
The Seventh Doctor comics from Marvel UK lead to crossovers with various other characters, and had a major impact on the canon of Death’s Head, the Marvel UK imprint’s biggest star for some years to follow.
The Daleks nearly turned out to be Servalan’s employers in Blake’s Seven, before someone realised this was a bit rich.
There have been a lot of Sherlock Holmes jokes in the show over the years, and even more lately for, er, some reason, but one of the New Adventures played the meeting out.
The Land Of Fiction is a place people can go to - and escape from.
And, of course, twenty years ago, the classic Doctors and companions faced the ultimate challenge - EastEnders! Even though each of these BBC titans is canonically fictional in the other...
Care should be taken when considering the settings’ mood, rules and general weird level. As did not happen in the case of EastEnders. A funny-looking guy in a police box will probably wreck a game of Vampire played as intended, but a game of Adventure! will shrug the effect off.