Jerry Koosman, the legendary Mets southpaw who helped lead the franchise to its first World Series title in 1969, died Sunday morning, the team said.

He was 83 years old.

Koosman was battling multiple illnesses, according to Jay Horwitz.

He was surrounded by family in Osceola, Wis.

Koosman was the winning pitcher in Game 2 of the 1969 World Series after the Orioles took Game 1, and he also won the Game 5 clincher.

A two-time All-Star, Koosman, whose No. 36 is retired by the Mets, had a 3.09 regular-season ERA across 12 seasons with the club.

He also had stints with the Twins, White Sox and Phillies.