Beloved actor Isiah Whitlock Jr. — perhaps best known for his catchphrase “Sheeeeeit…” from “The Wire” — has died … TMZ has confirmed.

The Hollywood veteran passed away peacefully Tuesday in New York following a short illness, his manager Brian Liebman tells us. Deadline was first to report his death.

Whitlock starred as corrupt Senator R. Clayton Davis on “The Wire” and had recurring roles on “Veep,” “Your Honor,” and “Atlanta.”

Whitlock collaborated with Spike Lee on several film projects, including “25th Hour” — where he originated his signature phrase — “BlacKkKlansman,” “Da 5 Bloods,” and “Chi-Raq.”

Whitlock’s manager Brian Liebman told Deadline, “Isiah was a brilliant actor and even better person. He was loved by all who had the pleasure to work with or know him. He will be greatly missed.”

He was 71.