Castle to Jake and the Fatman
7 connections
Castle
Law & Order
Hudson University from L&O also appears as the home of various victims and crimes in Castle,
Homicide: Life On The Street
Law and Order and Homicide crossed over on four episodes
The X-Files
Homicide's John Munch questioned The X-Files' The Lone Gunmen.
Veronica Mars
The mugshot of Malcolm T Wiggins from the X-Files episode "Titonus" appears on the wall of a police interrogation room in the Veronica Mars episode "Leave it to Beaver." Also the fictional car rental company Lariat where Mulder & Scully always rented their cars was featured prominently on the Veronica Mars episode "Rat Saw God."
Lost
In an episode of Veronica Mars, Veronica's fortune cookie had the numbers that won Hurley from Lost the lottery.
Diagnosis: Murder
The airplane that crashed and strand the cast of Lost was Oceanic Airlines Flight 815 also featured on Diagnosis Murder.
Jake and the Fatman
Diagnosis Murder was a spinoff of Jake and the Fatman.