The Golden Globe-winning drama about two Miami plastic surgeons who are best friends and business partners returns for its fourth season Sept. 5 on FOX.
Sanaa Lathan ("Love and Basketball") will appear in 12 episodes as a woman who buys the surgeons' practice. Hagman plays her much-older husband.
"I met with him, and I remember it was fun because when I was a kid I used to baby-sit my brother while watching `Dallas,'" show creator Ryan Murphy told the Television Critics Association's summer meeting Tuesday.
"All he kept saying in that first meeting was, `Do I get to have sex with her? Do I get to have sex with her?' And I said, `You came to the right show,'" Murphy said of Hagman.
Other guest stars announced Tuesday will be Catherine Deneuve, Richard Chamberlain, Kathleen Turner, Jacqueline Bisset, Melissa Gilbert and Peter Dinklage.
Deneuve will play a woman who wants her husband's cremated ashes put in her breast implants, Murphy said.
O'Donnell has been publicly outspoken against plastic surgery.
"She's getting a lot of heat now for doing a show that is about plastic surgery, to which she says, `Have you seen the show? The show is anti-plastic surgery. The show is about the idea that, for the most part, plastic surgery does not solve your problems,'" Murphy said.