Getty Images

As expected, quarterback Ben Roethlisberger announced his retirement on Thursday after 18 seasons with the Pittsburgh Steelers. The 39-year-old shared the news in a video posted to his social media pages.

In the video, No. 7 is seen cleaning out his locker while reflecting on nearly two decades in Pittsburgh. 

"I don't know how to put into words what the game of football has meant to me and what a blessing it has been ... The journey has been exhilarating, defined by relationships and fueled by a spirit of competition," he says in the video. "Yet the time has come to clean out my locker, hang up my cleats and continue to be all I can be to my wife and children. I retire from football a truly grateful man."

He then thanked his wife, his three kids, his parents and his sister. He also thanked his former coaches, teammates and the fans who supported him.

"Football has been a gift," the two-time Super Bowl champion said.

The Steelers drafted Roethlisberger in 2004 with the 11th overall pick and he spent his entire career in black and gold. Following his retirement announcement, fans and players reacted, some Steelers fans thanking him for the 18 years, some rivals celebrating the announcement and others reacting to a new era of quarterbacks emerging with each veteran QB retiring.

Here are some of the best reactions:

Tampa Bay Buccaneers quarterback Tom Brady joked about how different their training styles are.

The Steelers thanked Big Ben.

Eli Manning, the No. 1-overall pick in the 2004 NFL Draft and one of Roethlisberger's most notable contemporaries, congratulated him on his retirement.

Not a bad stat.

Fans are trying to manifest.

It's the end of an era.

Fans are already thinking five years ahead.