Hugh Hefner, the media titan who created Playboy magazine, died on Wednesday at the age of 91, and celebrities quickly took to social media to share their reactions to the news.

Hefner’s son, Cooper, released a statement after Playboy announced his death.

“My father lived an exceptional and impactful life as a media and cultural pioneer and a leading voice behind some of the most significant social and cultural movements of our time in advocating free speech, civil rights and sexual freedom,” he said. “He defined a lifestyle and ethos that lie at the heart of the Playboy brand, one of the most recognizable and enduring in history.He will be greatly missed by many, including his wife Crystal, my sister Christie and my brothers David and Marston, and all of us at Playboy Enterprises.”

In addition to releasing a statement to media outlets, Playboy wrote on Twitter, “American Icon and Playboy Founder, Hugh M. Hefner passed away today. He was 91. #RIPHef.”

A spokesperson for E!, which featured Hefner on the Playboy Bunny-focused “The Girls Next Door,” said in a statement, “Hugh was a true cultural icon and media pioneer who we had the pleasure of partnering with for ‘The Girls Next Door’ series, which debuted on E! in 2005 and aired for six successful seasons. Hugh will be dearly missed and we send our love to his family and friends as they celebrate his incredible life.”

Kendra Wilkinson-Baskett, a former Playboy Bunny and one of the three stars of “The Girls Next Door,” tweeted a heartfelt message about Hefner, along with a throwback photo of the two of them. “Can’t really put in to words how I really feel,” she wrote. “It’s easy to say he will be missed and how much I loved him. There’s a lot more than that.”

Reverend Jesse Jackson Sr. lauded his social advocacy, writing, “Hugh Hefner was a strong supporter of the civil rights movement. We shall never forget him. May he Rest In Peace.”

Models and actresses who appeared in Playboy, like Jenny McCarthy, also expressed their appreciation for Hefner. “RIP #Hef Thank you for being a revolutionary and changing so many people’s lives, especially mine,” she wrote. “I hope I made you proud.”

Others, like Nancy Sinatra, remembered their own encounters with Hefner, writing, “One of the nicest men I’ve ever known. Godspeed, Hugh Hefner.”

GLAAD President and CEO Sarah Kate Ellis, meanwhile, responded to media coverage of Hefner’s death with a critical statement: “It’s alarming how media is attempting to paint Hugh Hefner as a pioneer or social justice activist, because nothing could be further from reality. Hefner was a not a visionary. He was a misogynist who built an empire on sexualizing women and mainstreaming stereotypes that caused irreparable damage to women’s rights and our entire culture.”

See more reactions below.