Mark Blum, an Obie Award-winning New York stage and screen actor whose roles ranged from highly flawed husbands to overconfident blowhards, died on Wednesday in Manhattan. He was 69.

The actor Lee Wilkof, a close family friend, said the cause was complications of the coronavirus. Mr. Blum also had asthma.

Mr. Blum was an omnipresent figure in the Off Broadway world for decades, but his biggest moment in the spotlight came in 1989 after he played a time-traveling 20th-century playwright who befriends Gustav Mahler, in the Playwrights Horizons production of Albert Innaurato’s “Gus and Al.”

Frank Rich, in his review in The New York Times, referred to Mr. Blum’s “appealing, weary-eyed portrayal” and saw Al’s self-martyrdom as a form of “rueful hypersensitivity to the modern world.”

At the Obie ceremony, Mr. Blum was given one of 13 uncategorized Off Broadway performance awards for that season. His fellow winners included Nancy Marchand and Fyvush Finkel.

He had a notable Broadway career as well, appearing in nine productions over three and a half decades. He made his Broadway debut as a particularly versatile theater professional — playing an unnamed Venetian (one of four), understudying two roles and acting as assistant stage manager in “The Merchant” (1977), set in 16th-century Venice and inspired by a certain Shakespearean classic.

Other Broadway roles included Eddie, the young main character’s recently widowed and debt-ridden father, in Neil Simon’s “Lost in Yonkers” (1991), with Irene Worth; Spalding Gray’s campaign manager in “Gore Vidal’s The Best Man” (2000), a role he reprised as a replacement in the 2012 revival; Leo Herman, a.k.a. Chuckles the Chipmunk, the detestable host of a children’s television show, in “A Thousand Clowns” (2001); and Juror No. 1, the reasonable foreman, in “Twelve Angry Men” (2004).

At his death, he was an acting teacher at HB Studio in New York, where he headed the yearlong core training program named for Uta Hagen, and a faculty member at Brooklyn College.

In a video for HB, he reflected on one aspect of the study of acting.

“What is the journey of self-discovery that you begin on that allows you to join your own curiosity about who you are with your curiosity about what the human race is — and how to channel that into the work?”

Mark Jeffrey Blum was born on May 14, 1950, in Newark, to Morton Joseph Blum, an insurance executive, and Lorraine Pearl (Fink) Blum.

Growing up in nearby Maplewood, N.J., Mark thought casually about becoming a lawyer or an engineer; he was also something of a math prodigy. So when he entered the University of Pennsylvania, it was as a general liberal arts student with no particular goal. But he soon found his calling.

“Theater somehow enabled me to bring all the things that mattered into focus,” Mr. Blum told The New York Times in 1980. There was no formal theater program at Penn, but the administration helped him shape a curriculum, and he graduated as a theater major in 1972.

Two years later, he received a master of fine arts degree from the University of Minnesota in a special program in association with the Guthrie Theater in Minneapolis.

He made his New York stage debut as a post office clerk in a 1976 production of “The Cherry Orchard” at a theater on West 23rd Street.

While continuing to work onstage, he made his feature film debut in “Lovesick” (1983), Marshall Brickman’s romantic comedy about an unfaithful psychiatrist, and his television series debut as a doctor on “St. Elsewhere” in 1984.

He appeared in almost 30 films, including “Desperately Seeking Susan” (1985), as a married hot-tub salesman; “Crocodile Dundee” (1986); and “Shattered Glass” (2003). His most recent, “The Pleasure of Your Presence,” a romantic comedy about a wedding in the Hamptons, has been completed but not yet scheduled for release.

Over the decades he appeared on dozens of prime-time series — among them “Miami Vice,” “Roseanne,” “Frasier” and three shows in the “Law & Order” franchise — and he remained active into 2020. He appeared in 30 episodes of the Amazon series “Mozart in the Jungle” as Union Bob, a rules-obsessed symphony orchestra piccolo player. His most recent roles were on the drama series “You,” as a mysterious bookstore owner and stroke victim; “Succession” (2018-19); and “Billions,” in an episode scheduled to air in May.

His final Broadway appearance was in 2013 in “The Assembled Parties,” as Judith Light’s combative Upper West Side husband. His last Off Broadway productions were “Amy and the Orphans” (2018), at the Laura Pels Theater, in which he played an autistic woman’s generally oblivious brother; and “Fern Hill,” a comic drama about retirement-age baby boomers considering a commune, at 59E59 Theaters in September.

He is survived by his wife, the actress Janet Zarish; his mother; and his sister, Nancy Blum Litt.

Mr. Blum always had a special feeling for theater environments beyond Broadway. When he was appearing in Amy Herzog’s “After the Revolution” at the Williamstown Theater Festival in Massachusetts in 2010, he explained in a video interview that the place made him feel part of an artistic community “but also makes you feel enveloped by it in a way that supports you and elevates you.”

He added, “It’s like a little cushion underneath to prevent us from crashing to the earth.”