He was born into an artistically inclined family in Chicago, IL. His father was employed by the Art Institute of Chicago, while his mother was a one-time actress. He grew up in the Chicago suburb of Oak Park, where he attended Mann Elementary, then, soon to nurture his early theatrical inclinations, Oak Park-River Forest High School. At one point during his freshman year, he was about to try out of the OPRF track team, when his girlfriend convinced him to blow it off to audition for an upcoming stage production of the screwball comedy, "You Can't Take It With You." The school's advanced arts curriculum - he later likened it to New York's famous High School of Performing Arts - kept him busy year-round, and Lennon became such a well-regarded fixture on the theatrical calendar, that upon his 1988 graduation, his classmates voted him "Most Likely to Succeed." At age 16, he had met Kerri Kenney at a summer acting camp at Northwestern University, and the two agreed to meet again at NYU. Both were accepted and arranged to live on the same dorm floor. There, the couple met fellow student Robert Glen Garant, and they and eight other underclassmen formed the New Group comedy troupe. The group began with live sketch shows, later supplemented with short film and video segments, and played in NYU venues as wells as dining halls, bars, parks and other colleges; even securing an opening slot for comedian Dennis Miller in 1990. Along the way, Lennon transferred out of drama and into NYU's film school. His first feature film project would be in the lead role of "Aisle Six" (1991), the student film written and directed by fellow New Group member David Wain, Lennon playing a plumber-in-training who is angst-ridden over the stark realization that he really wants to be an electrician. In 1992, the New Group changed its name to The State and secured its first television work, "You Wrote It, You Watch It," a Jon Stewart-hosted show in which the troupe staged funny stories sent in by viewers, which would serve as springboard to their own show the next year called "The State" (MTV, 1993-95). The show come off as a sort of Generation-X Monty Python; edgier, more whimsical and absurdist than "Saturday Night Live" (NBC, 1975-) and other contemporaries, it garnered enough viewers to be a basic cable hit. MTV would have renewed again in 1995, but CBS came knocking, luring the troupe with plans for a series of primetime comedy specials and promises to groom that as the network's challenge to "SNL." But that fall's first special, "The State's 43rd Annual All-Star Halloween" (CBS, 1995), premiered with no promotion, rated poorly and CBS' programming chief terminated the group's contract, reputedly never having seen the show or having read the largely positive reviews.At loose ends, Lennon and the group returned to live work until 1997, when he, Garant, Kenney and fellow Statie Michael Ian Black created "Viva Variety," a bizarro variety show that lasted only a season on Comedy Central. After Lennon moved to Los Angeles (some Staties remained in New York), The State worked on three pilots for Fox, yet two projects never made it to production. The third a last-ditch attempt to use remaining funds to make an ultra-cheap send-up of the network's reality show "Cops," dubbed "Reno 911!" was offered up but Fox passed again. Lennon netted a few TV guest shots and eventually nabbed a supporting role on a short-lived medical dramedy, "MDs" (ABC, 2002-03), as well as slightly more substantial supporting film roles in light fare such as "Out Cold" (2002), "A Guy Thing" (2003) and "Heights" (2005). But in 2003, with reality TV now swamping the airwaves, Comedy Central gave new life to "Reno 911!" and Lennon, Garant, Kenney (now under her married name "Kenney-Silver") and ex-Statie Michael Patrick Jann brought the show to life. They would put omnipresent cameras on cops neither heroic nor comradely, but rather venal, stupid, mean-spirited and occasionally felonious many times over in one half-hour show, bringing in a parade of funny friends to portray perps or other guest characters. All scenes and dialogues improvised off simple premise outlines. Overseeing a rainbow of incorrigible-yet-somehow-loveable-loser deputies, including Garant as redneck Travis Junior and Kenney-Silver as dim, repressed Trudy Wiegel, Lennon played Lt. Dangle, whose authority and military bearing were curiously juxtaposed to his open, if underplayed, homosexuality and his uniform's ultra-short-shorts, not to mention his own susceptibility to his subordinates' incompetence.With "Reno" as a showcase, things got busier in the off-season. He supplied the voice of Eddie the computer in the feature film "The Hitchhiker's Guide to the Galaxy" (2005), and showed his first penchant to steal movies with a supporting role in the quirky indie film "The Godfather of Green Bay" (2005), and eventually landing a lead in the indie "Eden Court" (2007). Additionally, the Lennon/Garant team began picking up well-paid studio writing jobs, starting with a pass at the half-baked "Starsky & Hutch" (2004) script and "Taxi" (2004). Writing credits at that level often prove entrees to bigger things, even if through tepid Disney fare like "The Pacifier" (2005) and "Herbie Fully Loaded" (2005) and Fox's big-budget family action/comedy "Night at the Museum" (2006), a hit that secured them a bigger-budget sequel, "Night at the Museum: Battle of the Smithsonian" (2009), the latter of which provided Lennon with a supporting role. Their upper-tier work also helped them push through their own scripts, including much more R-leaning absurdist fare such as "Let's Go to Prison" (2006) and "Balls of Fury" (2007). Even with the occasional box office bomb on their filmography, Lennon and Garant always had the ongoing "Reno" as a touchstone to show prospective clients. They got a bigger showcase for their bread-and-butter project with the feature comedy "Reno 911! Miami" (2007), the uproarious big screen adventure, in which Lennon and team brought in reunited members of The State as various characters all up to various shenanigans. Meanwhile, Lennon had a series of higher-profile supporting roles in films like "Hancock" (2008), "I Love You, Man" (2009) - in which he famously shared a man-kiss with star Paul Rudd - and "17 Again," in which he played the nerd-weird best friend of Zac Efron. The New York Times' review cited Lennon for "nearly sprinting away with the movie."