The top two sci-fi franchises of all time continue to divide the geek community like the Death Star divided Alderaan, and for decades fans have been either team Star Wars or team Star Trek.
Now that's not to say you can't like them both fairly equally, but forced to choose in a "desert island" scenario fans will always choose one over the other.
And while the actors don't see a problem appearing in both franchises, especially when they're just doing voiceover work for an animated Star Wars series, the fans always have some gripe about their crossover appearance.
As this Looper video shows Trek alumni George Takei, Simon Pegg and Brent Spiner don't care if they catch heat from the fans about working in both universes. And Ron Perlman and Deep Roy don't get any grief about appearing in both franchises because they're too awesome to criticize.