BOSTON - He was a prolific producer of rebounds and record albums. And nicknames, too, as if at 7-foot-1 and 350 pounds he was too big for the simple "Shaq" that made him an instantly recognizable, one-name star in all of his endeavors.

Shaquille O'Neal had more than 28,000 points and almost 4 million Twitter followers. He appeared in six NBA Finals, three times as the MVP, and seven feature films, twice in a starring role.

A 15-time all-star, four-time champion, and the 2000 NBA most valuable player, the 39-year-old O'Neal announced his retirement on Twitter on Wednesday after spending most of his 19th season on the Boston Celtics bench, in street clothes because of leg injuries.

Along with a midafternoon tweet saying, "im retiring," O'Neal included a link to a 16-second video of him saying: "We did it; 19 years, baby. Thank you very much. That's why I'm telling you first: I'm about to retire. Love you. Talk to you soon."

An inveterate prankster who gave himself a new nickname - or several - in each of his six NBA cities, O'Neal did not notify his latest team, leaving it wondering about his plans. He played just 37 games this season, the first of a two-year deal at the veteran's minimum salary, making just three brief appearances after Feb. 1.

"He's a giant," commissioner David Stern said Wednesday at the NBA Finals in Miami. "He's physically imposing; he has an imposing smile. In the game, he imposed his will, and he has done it for quite a long time. It's been a great run, and we're going to miss him greatly."

O'Neal, 39, retires fifth all-time with 28,596 points, 12th with 13,099 rebounds, and with a .582 field goal percentage that is second only to Artis Gilmore among players with more than 2,000 baskets. His free-throw percentage of .527 - well, now is not the time to dwell on that.

"I'm a little bit sad," said Heat president Pat Riley, who also coached O'Neal when he won a title in Miami and watched Kareem Abdul-Jabbar, Patrick Ewing, and Alonzo Mourning when they retired. "It's been an honor to be part of coaching great, great players. And he will go down as one of the greatest of all time."

Appropriately, by early evening O'Neal's retirement became the No. 1 trending topic on the social networking site he embraced, and his former teammates and opponents took to Twitter to wish him luck.

"Shaq not only dominated the game of basketball but also dominated off the court w/ his big personality. Hes 1 of the greatest entertainers," Magic Johnson tweeted. "Thank you Shaq for leading the Lakers to 3 titles. We loved every minute of it!"

O'Neal spent three years at Louisiana State and was the big prize when the Orlando Magic won the 1992 draft lottery and selected him first overall. He took them from the lottery to the playoffs in two years, and then led them to the NBA Finals in his third year before they were swept by the Houston Rockets.

O'Neal signed with the Los Angeles Lakers in 1996 and had his greatest success there, winning three titles alongside Kobe Bryant and coach Phil Jackson. But amid tension between O'Neal and Bryant after a loss to the Detroit Pistons in the Finals, O'Neal was traded to the Heat in the summer of 2004.

After 31/2 years in Miami, a tenure that included his fourth NBA championship, O'Neal became a veteran for hire, moving to Phoenix and then Cleveland and finally Boston. But he couldn't deliver another title for Steve Nash and Amar'e Stoudemire with the Suns; with LeBron James with the Cavaliers; or with the Celtics' Big Three of Kevin Garnett, Paul Pierce, and Ray Allen.