Girls Next Door stars Kendra Wilkinson, Bridget Marquardt pay tribute to Hugh Hefner

Hugh Hefner’s The Girls Next Door costars and former “girlfriends” Kendra Wilkinson and Bridget Marquardt are among those mourning the Playboy founder, who died at age 91 on Wednesday.

Wilkinson and Marquardt, along with Holly Madison, starred in the E! reality series for six seasons from 2005 through 2010. Hefner’s eventual wife, Crystal Harris, and twins Kristina and Karissa Shannon joined the show in its final season in 2010.

“Hef changed my life. He made me the person I am today,” Wilkinson, who moved into the Playboy Mansion when she was just 18, said in a statement to PEOPLE. “I couldn’t be more thankful for our friendship and our time together. I will miss him so much but he will be in my heart forever.”

Later, Wilkinson posted on Twitter, “Thank you for all of your thoughts and condolences guys…. Can’t really put in to words how I really feel. It’s easy to say he will be missed and how much I loved him. There’s a lot more than that.”

“So sad but forever grateful for all the wonderful memories and amazing experiences #RIPHef #Playboy,” Marquardt wrote on Twitter and Instagram.

Madison has yet to release a statement.

The Shannon sisters claim to be appearing on Good Morning America Thursday which had not yet aired at the time of this post.

Hefner’s son Cooper, who is also the Chief Creative Officer of Playboy Enterprises, also released a statement regarding his father’s death and mentioned Crystal Harris Hefner, who has not yet shared any messages of her own.

“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.”