Sister show

Sister shows are two or more television series which exist in the same fictional universe and which may have crossovers. They differ to a degree from spin-offs in that shows may air simultaneously, rather than being derived from, and replacing, another. The popularity of most series is limited to a few seasons, and sister shows allow expanding the immediate audience and ratings share. This is accomplished by using mostly different actors and production facilities. Sister shows often shift styles or target audience slightly, for a larger overall market. Thus The Beverly Hillbillies emphasizes slapstick, while Green Acres emphasizes surreal humor.

Examples

• The Real World and Road Rules
• Band of Brothers and The Pacific.
• Grey's Anatomy and Private Practice.
• The King of Queens and Everybody Loves Raymond.
• CSI: Crime Scene Investigation, CSI: Miami, CSI: NY.

CSI: Crime Scene Investigation was joined by a sister show CSI: Miami in 2002, and a second, CSI: NY, in 2004. CSI and CSI: NY had crossovers with Without a Trace and Cold Case respectively in 2007.

• Hercules: The Legendary Journeys, Xena, Warrior Princess and Young Hercules.

The character Xena proved popular on Hercules and a second series started.

• Law & Order, Law & Order: Special Victims Unit, Law & Order: Criminal Intent, Law & Order: Trial by Jury, Law & Order: Los Angeles, Law & Order: UK, Homicide: Life on the Street and Conviction.
• NCIS, NCIS: Los Angeles and NCIS: New Orleans

NCIS is a spin-off from JAG; NCIS: Los Angeles had a crossover with the new 2010 Hawaii Five-0 series as well as the 2014 Scorpion series.

• All My Children and One Life to Live (which join General Hospital).

From 2004 to 2005, they featured a crossover storyline told on both series.

• Stargate SG-1, Stargate Atlantis and Stargate Universe.

Stargate Atlantis premiered during the eighth season of Stargate SG-1. Both occasionally had crossover plots. Stargate Universe likewise featured crossover character appearances.

• Star Trek: The Next Generation, Star Trek: Deep Space Nine, Star Trek: Voyager and Star Trek: Enterprise.

Deep Space Nine began during the sixth season of The Next Generation. Several characters from the older series appeared in the newer, but only one episode of the older ("Birthright") had characters from the newer. All the Star Trek series are in the same universe, and there were many shared concepts and characters.

• Petticoat Junction, Green Acres and The Beverly Hillbillies.

All three take place around the town of Hooterville. Guests appear in Green Acres, although the plots are not linked.

• The Trumptonshire series had Camberwick Green, Trumpton and Chigley villages in the same area. Gordon Murray stated that the area of "Trumptonshire" is "representative of real locations which are one-and-a-half miles from each other in an equidistant triangle". Several characters appear in guest roles in other villages.
• The Young and the Restless and The Bold and the Beautiful.

Known for frequent crossovers, the latter was planned by William J. Bell to be a sister show. Characters have gone between the two series regularly since the 1990s.

• As the World Turns, Guiding Light and Another World (which join Days of Our Lives).

Guiding Light was joined by a sister show, As the World Turns, in 1956 and was also joined by another sister show, Another World, in 1964.

• Buffy the Vampire Slayer and Angel.
• Family Guy, The Cleveland Show and American Dad!.
• The Simpsons and Futurama.
• Phineas and Ferb and Milo Murphy's Law
• The X-Files, Millennium and The Lone Gunmen.

Although The X-Files and The Lone Gunmen are explicitly linked, mostly through several shared characters and plot threads, the connection to Millennium is only concretely expounded in one episode of The X-Files and one episode of Millennium.

• Eureka, Warehouse 13 and Alphas.
• Ally McBeal, The Practice, Boston Public and Boston Legal.

All created by David E. Kelley and set in Boston.

• Casualty, Holby City and HolbyBlue.
• Doctor Who, Torchwood, The Sarah Jane Adventures, K9 and Class.
• Hawaii Five-O, Magnum, P.I., Simon & Simon and Murder, She Wrote
• Battlestar Galactica and Caprica.

Caprica takes place 58 years before the events in Battlestar Galactica.

• The Flintstones and The Jetsons.
• The Fairly OddParents, Danny Phantom, T.U.F.F. Puppy and Bunsen Is a Beast
• The Honeymooners and Here's Lucy.
• 77 Sunset Strip, Hawaiian Eye, Surfside 6 and Bourbon Street Beat.
• The Man from U.N.C.L.E and The Girl from U.N.C.L.E..
• Batman and The Green Hornet.
• Jake and the Fatman, Diagnosis: Murder and Matlock.
• Las Vegas and Crossing Jordan.
• One Tree Hill and Life Unexpected.
• Bones, The Finder, Rosewood and Sleepy Hollow.
• The Mary Tyler Moore Show, Rhoda, Phyllis and Lou Grant.
• All in the Family, The Jeffersons, Maude, Archie Bunker's Place and Good Times.
• Happy Days, Laverne & Shirley, Joanie Loves Chachi and Mork & Mindy.

Happy Days is a spin-off of Love, American Style.

• The Love Boat, Charlie's Angels and Fantasy Island.
• The Dukes of Hazzard, Enos and The Dukes.
• Cheers, Wings, Frasier, Caroline in the City, Friends, Mad About You and The John Larroquette Show.
• Lilo & Stitch: The Series, American Dragon: Jake Long, The Proud Family, Kim Possible and Recess.
• Golden Girls, The Golden Palace, Nurses and Empty Nest.
• The Vampire Diaries and The Originals.
• Pretty Little Liars and Ravenswood.
• Arrow, The Flash, Legends of Tomorrow, Supergirl, Constantine and Vixen

Supergirl and Constantine were tied into the same continuity after their first seasons had finished (neither of which were on The CW, unlike the other shows)

• Agents of S.H.I.E.L.D., Daredevil, Agent Carter, Jessica Jones, Luke Cage, Iron Fist, The Defenders, the Punisher, Inhumans

Part of the larger Marvel Cinematic Universe

• Chicago Fire, Chicago P.D., Chicago Med and Chicago Justice
• Ultimate Spider-Man, Avengers Assemble and Hulk and the Agents of S.M.A.S.H.