Angel to Supernatural
3 connections
Angel
Buffy the Vampire Slayer
Angel was a spin-off of Buffy the Vampire Slayer.
The X-Files
The X-Files? Cigarette Smoking Man and Buffy the Vampire Slayer's Spike both smoked Morley cigarettes.
Supernatural
Characters on Supernatural rented cars from the fictional Lariat Rent-A-Car which Mulder and Scully rented from on The X-Files