BALTIMORE — In good times, DeAndre McCullough inspired nearly everyone he touched. He was a small-time drug dealer made good, a recovering addict who had a fledgling career counseling troubled teenagers. He played bit roles on HBO in “The Wire” and in “The Corner,” which chronicled his life in the drug trade at the age of 15.

He had survived the inner-city whirlpools that swallowed so many people he knew. His father and several friends lost their lives to drug overdoses or gunfire. Mr. McCullough, who abused cocaine and heroin, never expected to live past 20.

“I’m 35 today,” he marveled in a text message that he sent to his mentor, David Simon, the writer and television producer, in May. “Never thought I’d make it. How ’bout that?”

But on Aug. 1, Mr. McCullough was found dead of heroin intoxication, making him a powerful symbol of the urban maelstrom that has devoured so many young men. To the people who knew him, his death was all the more heartbreaking because a better life had seemed so tantalizingly within his reach.