Star Trek has the Enterprise: Dr Who has his Tardis. Star Trek has a crew: Dr Who is a lone wolf (except for his companions.) Star Trek has Romulons, the Borg, and Q: Dr Who has Cybermen, Daleks, and the Master. Star Trek's prime directive is "Do not try to change a culture": Dr Who's prime directive is "Do not try to change history." Star Trek can only occassionally go through time: Dr Who does it all the "time!"