The comedy series, which will kick off its third season in June, will feature Sykes in the fifth episode as Judge Yvonne Wright, who presides over a case inspired by Mississippi high school senior Constance McMillen, who was denied access to her prom because she wanted to attend with her girlfriend.
Shenkman will have a recurring role as love interest to lead character Jane, played by Broadway veteran Brooke Elliott, and Goldwyn will guest in episode six as a corrupt DA who formerly dated Jane.
"Drop Dead Diva" centers on Jane, a brilliant, plus-size attorney whose body was taken over by the spirit of Deb, "a shallow model-in-training."
Sykes recently starred as Miss Hannigan in Media Theatre's production of Annie and concluded her run in January 2011. Goldwyn was last seen on Broadway in the revival of Promises, Promises, and Shenkman's credits include Sight Unseen, Proof and The Deep Blue Sea.
The cast of the Lifetime series also includes stage performers Margaret Cho, Josh Stamberg and Kate Levering.
For more information, visit Drop-Dead-Diva.