One of the greatest basketball players in the history of the game is calling it quits.

Four-time NBA champion Shaquille O'Neal is retiring. He first announced his retirement on a Twitter video.

"We did it. Nineteen years, baby. I want to thank you very much. I'm about to retire," he said in the video.

Shaq won three NBA championships with the Los Angeles Lakers and one with the Miami Heat.

The basketball great won the NBA MVP award in the 1999-2000 season. He also was the MVP of the NBA Finals three times while with the Lakers.

Shaq was originally drafted by the Orlando Magic No. 1 overall in the 1992 draft. He left Orlando for the bright lights of Los Angeles after the 1996 season.

During his Lakers tenure, Shaq famously feuded with Kobe Bryant while winning three consecutive NBA championships from 2000-2003. He was traded to the Miami Heat after the 2004 season when the Lakers were stunned in the NBA Finals by the Detroit Pistons.

He also played for the Phoenix Suns, the Cleveland Cavaliers and the Boston Celtics during his career.

He crossed over to Hollywood stardom during his playing career, starring in the movies "Blue Chips" and "Kazaam."

He finishes his career averaging 23.7 points-per-game and 10.9 rebounds-per-game.