He got his start onstage, though; the Bronx native acted in such off-off-Broadway shows as "The Brick and the Rose", "Liverpool Fantasy", "Romeo and Juliet" and "The Sea Gull" in the early 80s while earning degrees from SUNY Albany and the Yale School of Drama. Simultaneously, Altman earned a living teaching at an alternative high school in Manhattan.
By the mid-80s, Altman was also moonlighting on TV, appearing on such New York-based shows as "The Equalizer", "Law & Order" and the ABC soap opera "One Life to Live". Later, in the 90s, he would also turn up on "Touched by an Angel" and "The Cosby Mysteries," was featured as one of the ill-fated white water rafters in "White Mile" (HBO, 1994) and had a recurring role in the short-lived drama "Nothing Sacred" (ABC, 1997).
But Altman's real opportunities have come from good supporting roles on the big screen. His debut was as Harrison Ford's best friend in Mike Nichols' under-performing "Regarding Henry" (1991). Better was his turn as Stephen Collins' best friend in Stacy Cochran's low-budget, dark comedy "My New Gun" (1992). Smaller roles followed in the hit adaptation "Glengarry Glen Ross" (1992), the baseball comedy "Rookie of the Year" (1993) and in the title role--though a small one--in Anthony Minghella's "Mr. Wonderful" (also 1993). Additional supporting roles followed in "Mr. Jones" (1993), Ron Howard's "The Paper" and Robert Redford's Oscar-nominated "Quiz Show" (both 1994).
Altman seemed to have better luck in small, low-budget films such as the Canadian drama "Vibrations" (1995), the dark, edgy comedy "Rescuing Desire" (1996), and the Oscar-winning short comedy "Dear Diary" (1996), starring Bebe Neuwirth, which began life as a TV pilot. One of his best film roles to date was as a visiting pal of the mourning Peter Gallagher in "To Gillian on Her 37th Birthday" (1996). Altman began specializing in educated, authrotative character parts, regularly essaying lawmen, doctors, lawyers and professors on film in pictures such as "Cop Land" (1997), "The Object of My Affection" (1998), "Girl Interrupted" (1999), "L.I.E." (2001) and "Changing Lanes" (2002). Altman snared a highly visible and career-bolstering role as Nicolas Cage's psychiatrist in "Matchstick Men" (2003).