Born David M. Eigenberg in the Long Island hamlet of Manhasset, NY, he was the middle child and only son of Beverly, a preschool provider, and Harry, a CPA. At the age of four, Eigenberg moved with his family to Illinois, eventually putting down stakes in the town of Naperville, where he received his first theatrical experience at the age of 12 in a production of Kurt Vonnegut, Jr.'s "Happy Birthday, Wanda June." Although a few more stage performances followed over the coming years, he focused primarily on sports, such as wrestling and football, during his time at Naperville Central High School, before graduating in 1982. Although Eigenberg had been accepted to the University of Iowa, the venture lasted a mere five weeks before he was back in Naperville, looking for work. Following a stint in the U.S. Marine Corp., Eigenberg found himself in the Chicago area in 1986, and he began taking classes at an area trade school. With little to do after the school district went on strike, he auditioned for a role in a production of "One Shining Moment" on a whim. To his surprise, Eigenberg landed the role, alongside future TV star Megan Mullally, and enrolled at the prestigious American Academy of Dramatic Arts in New York shortly afterward.Like thousands of other aspiring actors, Eigenberg spent the next several years auditioning for roles while supporting himself with various odd jobs. Early on, he had little to show for his efforts, other than a tiny role that marked his feature film debut in the modern day hippie comedy "Rude Awakening" (1989), starring Cheech Marin and Eric Roberts. Things began to happen for the young actor the following year when he won the small, but affecting role of a nameless hustler in John Guare's "Six Degrees of Separation" on Broadway in 1990. Eigenberg kept the ball rolling with small parts in the metaphysical comedy "In the Spirit" (1990), and a supporting turn in "By a Thread" (1991), an independent psychodrama featuring future Oscar winner Melissa Leo. He appeared alongside Cuba Gooding, Jr. in the near-future drama "Daybreak" (HBO, 1993), and was later used to good effect in an especially memorable 1996 episode of "Homicide: Life on the Street" (NBC, 1993-99), playing an all-too-enthusiastic witness to a sniper attack who turns out to be the murderer. The strong notices earned him a recurring role as a D.A. in the David E. Kelley legal drama "The Practice" (ABC, 1997-2004) in 1997. After an eight-year absence from the big screen, Eigenberg returned to feature films with an appearance in the Michael Douglas/Gwyneth Paltrow thriller "A Perfect Murder" (1998). He next proved something of an unlikely action hero as a regular on the second season of the mercenary action series "S.O.F. Special Ops Force" (syndicated, 1997-99). Although "S.O.F." never completed its mission, Eigenberg finally found his breakthrough role, when after numerous auditions for several other parts, he was cast in 1999 as Steve Brady, the unassuming, eternally patient boyfriend of Miranda Hobbes (Cynthia Nixon) - the type-A personality gal pal of Carrie Bradshaw (Sarah Jessica Parker) - on the immensely popular series "Sex and the City" (HBO, 1998-2004). Originally written as a temporary fixture - the fate of most males on the show - Eigenberg's character proved so popular that he remained on the series throughout the remainder of its run, eventually fathering a child and moving to Brooklyn with Miranda, much to her initial dismay. Elsewhere on television, a regular series role in Barry Levinson's police drama "The Beat" (UPN, 2000) alongside Mark Ruffalo did not quite take Eigenberg's career to the next level when it was canceled after a mere handful of episodes.Despite the disappointment of "The Beat," Eigenberg maintained a noticeable presence on television with a 2001 recurring role on the comedy series "Ed" (NBC, 2000-04) as the genius romancer of the two single female leads (Julie Bowen and Leslie Boone). The following year saw him in his biggest film role up to that point, as a journalist colleague and friend to Richard Gere in Mark Pellington's eerie thriller "The Mothman Prophecies" (2002). In a change of pace, Eigenberg voiced the character of the self-described "cutest cat in the world," Nermal, in the live action-animation adaptation of the long-running comic strip "Garfield" (2004), starring Bill Murray voicing the lasagna-loving furball. That same year, he picked up a supporting role in the little-seen familial dramedy "Around the Bend" (2004), starring Josh Lucas and Christopher Walken. Guest spots on several popular series such as the police procedural "CSI: Crime Scene Investigation" (CBS, 2000-15) and "ER" (NBC, 1994-2009) were interspersed with big screen reprisals of Steve for the cinematic spin-offs "Sex and the City" (2008) and "Sex and the City 2" (2010). After appearing in episodes of "The Game" (The CW/BET, 2006-15) and "Law & Order: Special Victims Unit" (NBC, 1999-), Eigenberg returned to regular series status on "Chicago Fire" (NBC, 2012-), playing a down-on-his-luck firefighter who is injured on the job, but quickly recovers and helps his crew overcome the death of a fellow firefighter.