Acting and performing While Lennon was a member of The New Group, the comedy troupe changed its name to
The State. As they performed material at theaters and clubs in New York City, they worked on the
MTV show
You Wrote It, You Watch It. This led to their self-titled series
The State, which ran from 1993 to 1995 on
MTV. It was nominated for a 1995
Cable Ace Award for Best Comedy Series. In the same year, they created ''The State's 43rd Annual All-Star Halloween Special'' for
CBS. After the departure of
The State from MTV and failed long-term deals with both
ABC and CBS, Lennon, along with Kenney,
Robert Ben Garant, and
Michael Ian Black, created and starred in the
Comedy Central program
Viva Variety (1997–99). The show was based on "The Mr. and Former Mrs. Laupin Variety Programme," a sketch which Lennon had written for the final season of
The State.
Viva Variety received a 1997
Cable Ace Award nomination for Best Comedy Series. After
Viva Variety, Lennon, Kenney, and Garant created and starred in
Reno 911! (2003–09). The series was initially slated to be on
Fox, but the channel rejected it for being too risqué and the program ended up on
Comedy Central. Lennon has appeared as a guest star in dozens of TV shows including
The League,
Childrens Hospital,
Party Down,
New Girl,
How I Met Your Mother,
Comedy Bang! Bang!, and ''
Don't Trust the B---- in Apartment 23''. One of his notable guest starring roles was as
Joey Tribbiani's blackjack-dealing "identical hand twin" on the
Friends fifth-season finale ("The One In Vegas", Pts. I and II). Additionally, he has appeared on
Jimmy Kimmel Live!,
The Tonight Show,
The Daily Show,
Late Night with Jimmy Fallon and with 31, had the second-highest number of appearances on
The Late Late Show with Craig Ferguson. In 2008, he began doing stand-up comedy, occasionally playing guitar, and incorporating music. He appeared on
The Meltdown with Jonah and Kumail, ''
John Oliver's New York Stand-Up Show, The Jeselnik Offensive, and The Benson Interruption''. He was the guest on the first episode of
Chris Hardwick's
The Nerdist Podcast, which was recorded in Lennon's garage. In 2010, Lennon and Garant created and starred in a sitcom pilot,
The Strip, for
NBC. In May of that year, NBC announced that it would not produce it as a series. In November and December 2011, Lennon filled in as guest voice for the robot sidekick
Geoff Peterson on the CBS show
The Late Late Show with Craig Ferguson. Lennon has appeared in many films including
Bad Teacher,
Memento,
How to Lose a Guy in 10 Days,
Transformers: Age of Extinction, and
I Love You, Man, for which he and co-star
Paul Rudd were nominated for a 2009
MTV Movie Award for Best Kiss. In two of
Christopher Nolan's films,
Memento (2000) and
The Dark Knight Rises (2012), Lennon played a doctor. He played Felix Unger in the 2015–17 television series
reboot of
The Odd Couple opposite
Matthew Perry, who played Oscar Madison. In 2016, he co-starred as a scientist in
Paramount Animation's
Monster Trucks and began a recurring role on the Fox action sitcom
Lethal Weapon as Leo Getz, a character which was previously portrayed on film by
Joe Pesci. At the 2016
People's Choice Awards ceremony, Lennon participated in an on-stage sketch parodying a recent gaffe by
Steve Harvey at the
Miss Universe 2015 pageant. In 2020 and 2021, he had a recurring role in
Supergirls
fifth and sixth seasons as
Mr. Mxyzptlk, taking over from
Peter Gadiot. In 2020, Lennon reprised his role as Lieutenant Jim Dangle in the seventh season of
Reno 911! which aired on
Quibi. He appeared in the 2021 film
Reno 911! The Hunt for QAnon. The eighth season of the series, now titled
Reno 911! Defunded, premiered on
The Roku Channel in February 2022. In 2023, he was cast in the
Zoey 101 reboot,
Zoey 102. The film was released on July 27, 2023, on
Paramount+.
Screenwriting Lennon is a successful screenwriter and
script doctor. Most of his screenplays are written in collaboration with writing partner Robert Ben Garant. Among Garant and Lennon's credits are the
Night at the Museum films, the 2005 Disney comedy
The Pacifier and the 2006 prison comedy ''
Let's Go to Prison''. In 2010,
FX Network ordered a
pilot episode for a Garant/Lennon
science fiction television comedy called
USS Alabama, set 1000 years in the future aboard a
United Nations Peacekeeping spaceship, the U.S.S.
Alabama. Garant and Lennon are credited as story co-writers for the film version of
Baywatch (2017). Lennon is the author of four of
IFC's "50 Greatest Comedy Sketches of All Time".
Novels and stage Lennon has written three
young adult novels:
Ronan Boyle and the Bridge of Riddles,
Ronan Boyle and the Swamp of Certain Death, and
Ronan Boyle into the Strangeplace.
Ronan Boyle and the Bridge of Riddles debuted on
The New York Times Best Seller list. He wrote the book for the theatrical production of
Trading Places: The Musical! which debuted at the
Alliance Theatre in
Atlanta in June 2022. ==Personal life==