Hugh Laurie
Hugh Laurie is one of the worst connected actors on the show. Although he has other minor connections, until 2011, the only two on-screen actors he has appeared with outside of the series were Scott Michael Campbell (in Flight of the Phoenix, when on location filming he made his breakthrough audition tape) and Leighton Meester (in The Oranges, where he plays a character who is obsessed with her). He finally has increased his total to five:
- Tiffany Espensen in the animated movie Hop and Two Stories
- Judy Greer in Tomorrowland and Here Kitty
- Randall Park on Veep and Autopsy
Lisa Edelstein
Lisa Edelstein has an extensive television resume and is very well connected.
Girlfriends' Guide to Divorce
- With Beau Garrett in 26 episodes and in Remorse
- With Alanna Ubach in 19 episodes and in Spin
- With Suzanne Ford in "Rule 58: Avoid the Douchmobile" and in Histories
Others
- With Tracy Vilar in two episodes of ER and four episodes of House, M.D.
- In the Scandal episode "Top of the House"
- With Joshua Malina (reunited in Wilson)
- With Jay Karnes (reunited in The Social Contract)
- With Kurt Fuller (reunited in Poison)
- With Elle Fanning in Daddy Day Care and Need to Know
- On The Legend of Korra
- With Aaron Himelstein (reunited after The Socratic Method)
- With Darcy Rose Byrnes (reunited after The Social Contract)
- With D.B. Sweeney (reunited after Who's Your Daddy?)
- In Blue-Eyed Butcher
- With David Marciano (reunited in The Tyrant)
- With Vyto Ruginis (shared the cross-examination scene in Words and Deeds)
- In the Miss Match episode "Forgive and Forget"
- With Hamilton Mitchell (reunited in Hunting)
- With Skyler Gisondo (reunited in Cane and Able)
- In the TV Movie Mrs. Harris
- With Frank Whaley (reunited in Mirror Mirror)
- With John Patrick Amedori (reunited from Poison)
- With John Rubinstein (reunited from The Mistake)
- With Caroline Lagerfelt (reunited in Guardian Angels)
- With Vicki Davis (reunited in Ignorance is Bliss)
- With Greg Grunberg in Sex Kills and the Felicity episode "Raising Arizona"
- With Ana Lucasey in Known Unknowns and She Loves Me Not
Omar Epps
Omar Epps is not terribly well connected, but does have some important connections.
- Epps has worked with Charles S. Dutton in several other projects, including Against The Ropes and Conviction. They play son and father in Euphoria (Part 2) and Family
- With Michelle Clunie on ER and No Reason
- With David Marciano on Shooter and in The Tyrant.
Robert Sean Leonard
Robert Sean Leonard is fairly well connected for an actor whose primary career is on Broadway.
- With Cynthia Nixon in The Manhattan Project and Deception
- With Frank Whaley in Swing Kids and Mirror Mirror
- With David Strathairn in In the Gloaming and Lockdown
- With Mackenzie Astin in The Last Days of Disco and All In
- With Jack Plotnick in Ground Control and Broken
- With Sasha Alexander on Wasteland and The Down Low
- With John Larroquette in Corsairs and Son of Coma Guy
- With Geoffrey Lewis in A Painted House and One Day, One Room
- With Anthony Tyler Quinn in Killer: A Journal of Murder and 5 to 9
- With Piper Perabo in The I Inside and Resignation
- With Harry J. Lennix on The Blacklist and DNR
- With Andre Braugher on Law & Order: SVU and four episodes of House, M.D.
- With Jessy Schram on Falling Skies and in Needle in a Haystack
Dead Poets Society
- Played Kurtwood Smith's son and appeared with him in Half-Wit
- Appeared with Dylan Kussman and reunited in Kids
Driven
- With Kip Pardue in Forever
- With Stacy Edwards in The Socratic Method
- With Brent Briscoe in Three Stories
Kal Penn
Kal Penn has numerous connections (most importantly, John Cho), but due to his short term on the show, not too many reunions
- With Reynaldo Rosales in Homeland Security and 97 Seconds
Jennifer Morrison
Jennifer Morrison has become much better connected since she left the show, particularly because of her work on Once Upon a Time.
- In the TV Movie Five, she appears with Lyndsy Fonseca (Resignation), Carla Gallo (Act Your Age), Andrea Bendewald (TB or Not TB) and Trever O'Brien (Moving the Chains)
- Appears with Salvator Xuereb in Big Stan and Joy
- Appeared with Akiko Morison in Intersection and Detox
- Appeared with David Bowe in Grind and The Jerk
Once Upon A Time
- With Elizabeth Mitchell in ten episodes and in Damned If You Do
- With James Immekus in three episodes and in Distractions
- With Skyler Gisondo in "Good Form" and in Cane and Able
- With Bailee Madison in three episodes and in Act Your Age
- With Jessy Schram in three episodes and in Needle in a Haystack
Jesse Spencer
Spencer had a limited resume before joining House, but his starring role on Chicago Fire has increased his connections and reunions.
- With Carmen Electra in Uptown Girls and Three Stories
Chicago Fire
- With Christopher Cousins in two episodes, as well as in Distractions
- With Elias Koteas in "You Will Hurt Him" and No Reason
- With Dylan Baker in "A Dark Day", "No Regrets" and A Pox on Our House
- With Yaya DaCosta in eight episodes, as well as Runaways and Perils of Paranoia
- With Sara Holden in "Real Never Waits" and 97 Seconds
Chicago P.D.
The episode "8;30 P.M." features Spencer with Jon Seda (Brave Heart), Elias Koteas and Dylan Baker
Peter Jacobson
Jacobson has a lengthy resume and numerous connections
- With Dennis Kieffer in The Lost Room episode "The Key and the Clock" and Not Cancer. The episode also featured Elle Fanning.
- In the Ray Donovan episode "Twerk" he appears with Frank Whaley (also in Mirror Mirror) and Doug McKeon (also in Brave Heart)
- In the Method & Red episode "Dogs", he appears with Candace Kita (also in Out of the Chute). Carmen Electra also appears in the episode.
White House Down
- With Jimmi Simpson (reunited from Unfaithful)
- With Jake Weber (reunited from Man of the House)
Colony
- Co-stars with Sarah Wayne Callies (reunited from Open and Shut) and Tory Kittles
- With Keiko Agena in three episodes and Unplanned Parenthood
- With Jill Remez in "Gateway" and Saviors
- With Gonzalo Menendez in "Gateway" and Private Lives
Olivia Wilde
Wilde isn't very well connected, but has several important connections
- With Douglas Spain in Fix and 97 Seconds
- With Trever O'Brien in In Time and Moving the Chains
- With Robert Lee Bell in People Like Us and The Fix
The Words (2012)
- Also appeared with Zeljko Ivanek in Last Resort
- Also appeared with Brian Klugman in 97 Seconds
Amber Tamblyn
Amber Tamblyn is fairly well connected, generally due to her starring roles in Joan of Arcadia before the series and Two and a Half Men after the series.
Joan of Arcadia
- Chris Marquette played her on-again/off-again boyfriend Adam Rove and they reunite in Fall From Grace
- In Requiem, she and Marquette also appear with Aaron Himelstein, Brian Klugman, Todd Louiso and Xhercis Mendez
Two and a Half Men
- With Paula Marshall in two episodes as well as Family Practice and Bombshells
Odette Annable
- With Alexis Raben on Banshee and in We Need the Eggs
- With Shane Schoeppner on Breaking In and in Love is Blind
Charlyne Yi
Yi has a few connections, but only two reunions. She had previously worked with Odette Annable, and appeared with George Sharperson in both All About Steve and We Need the Eggs
Multiple Main Cast Members
- Amber Tamblyn and Odette Annable were both in three episodes of Two and a Half Men and Everybody Dies. They were joined in two episodes of "Men" by D.B. Sweeney
- Odette Annable and Charlyne Yi were both in Cloverfield and spent most of Season 8 together. Brian Klugman and Maria Zambrana also appeared in Cloverfield.
- The 2006 movie Flourish starred Jennifer Morrison, Jesse Spencer and Leighton Meester, who also all appeared together in Informed Consent and Lines in the Sand. The movie also features Aulani Rhea, who appeared with Morrison and Spencer in Words and Deeds, Insensitive and House Training
- Kal Penn was a regular on Battle Creek and in the episode "Sympathy for the Devil" was joined by Robert Sean Leonard and Meredith Eaton