His
Supergirl Returns series is excellent and has lots of crossovers. DC Universe (movieverse) / NCIS / West Wing / Bones / Dr. Who / NCIS LA / Rockford Files / Castle / Hancock / Batteries Not Included / Torchwood / Avengers(UK) / SJA / Buffy / Veronica Mars / West Wing / Warehouse 13 / Stargate / Young Wizards. Many of those are just one shot cameos or dimension hopping but several are through the whole series.
