That ’70s Show’: Kurtwood Smith Mourns On-Screen Mother-in-Law Betty White

That ’70s Show star Kurtwood Smith was among the many Hollywood stars to pay tribute to Betty White, who died just weeks shy of her 100th birthday. Smith shared the screen with White in four episodes of That ’70s Show, in which White played Smith’s on-screen mother-in-law, Bea Sigurdson. White died on Friday at 99.

“It’s a sad end to the year.. losing such a wonderful comedic genius,” Smith wrote. “More than that, [Betty White] was a wonderful person! It was a treat to know her and a privilege to work with her.” Smith starred in That ’70s Show as Red Forman, the father of Eric (Topher Grace). Debra Jo Rupp played Smith’s on-screen wife, Kitty Forman. Kitty’s parents Bea and Burt Sigurdson were played by White and Tom Poston. Smith’s post included a photo of White with Rupp and Poston from the ’70s Show set.

White died on New Year’s Eve, after a seven-decade career that stretched from the birth of television to the streaming era. She “died peacefully in her sleep at her home,” her agent Jeff Witjas told PEOPLE, which had just prepared an issue about her centennial.”Even though Betty was about to be 100, I thought she would live forever,” Witjas continued. “I will miss her terribly and so will the animal world that she loved so much. I don’t think Betty ever feared passing because she always wanted to be with her most beloved husband Allen Ludden. She believed she would be with him again.”

White’s incredible career began in the mid-1940s and she soon became the queen of a new medium, television, during the 1950s. She won five Emmys, including two for The Mary Tyler Moore Show, one for The Golden Girls, another for The Jon Larroquette Show, and her final one for hosting Saturday Night Live in 2010. In 2015, she received the lifetime achievement award at the Daytime Emmy Awards.

Smith and Rupp will reunite for That ’90s Show, a sequel series in development at Netflix. The project was announced in October and will run at least 10 episodes. That ’90s Show will start in 1995 and sees Leia Forman moving in with her grandparents. The show will introduce a new batch of characters as Leia’s friends in Point Place, Wisconsin. That ’70s Show creators Bonnie Turner and Terry Turner will return as writers and executive producers. Casting for the new series has not been announced yet.