Buffy the Vampire Slayer to Doctor Who (1996) [pilot only]
3 connections
Buffy the Vampire Slayer
Angel
Angel was a spin-off of Buffy the Vampire Slayer
Red Dwarf
In the Red Dwarf episode "Psirens", the crew of the Red Dwarf come across a space ship graveyard which includes a Weyland-Utani ship, connecting it with Angel.
Doctor Who (1996) [pilot only]