I loved where in sitcom, there was the characters you could not see. Sometimes they eventually gave the character an actor but some purposefully never showed their face. Sometimes they had a voice and other times no voice.
Maris Crane from Frasier
Maris Crane is Niles Crane's wife for the majority of the show Frasier until he divorces her. Though she is never fully seen onscreen (much like Norm Peterson's wife, Vera, on Cheers), she is the most notable of the show's never-seen characters, and often the subject of many jokes. Maris makes only two onscreen "appearances": "Voyage of the Damned" when her shadow is seen through a shower curtain, and in "Rooms with a View", where she appears in Niles' memory, almost completely covered by bandages after surgery. When David Hyde Pierce guest starred on the Simpsons, the writers wanted him to call a character 'Maris' but the Frasier writers didn't approve so it was changed to Bart covering his eyes and him asking if he was Maris. I liked this, Simpsons writers did not understand this. I liked both shows and followed both.
Maris Crane from Frasier
Maris Crane is Niles Crane's wife for the majority of the show Frasier until he divorces her. Though she is never fully seen onscreen (much like Norm Peterson's wife, Vera, on Cheers), she is the most notable of the show's never-seen characters, and often the subject of many jokes. Maris makes only two onscreen "appearances": "Voyage of the Damned" when her shadow is seen through a shower curtain, and in "Rooms with a View", where she appears in Niles' memory, almost completely covered by bandages after surgery. When David Hyde Pierce guest starred on the Simpsons, the writers wanted him to call a character 'Maris' but the Frasier writers didn't approve so it was changed to Bart covering his eyes and him asking if he was Maris. I liked this, Simpsons writers did not understand this. I liked both shows and followed both.
Vera Peterson from Cheers
Norm has a wife named Vera who is often mentioned but her face is never seen. When she is finally shown, her face is covered in pie thrown by Diane (season 5, episode 9 Thanksgiving Orphans), and the actress is uncredited. The only other times she is seen, viewers can see only her legs and at one time her waving from a car which drives past cheers on her and Norm's 15th wedding anniversary. Vera is the brunt of many of Norm's jokes, but on many occasions, Norm has professed secretly an undying love for his wife, or defended her honor.
Dick from Cybill
Maryann Thorpe– Cybill's best friend had am unfaithful ex-husband, celebrity plastic surgeon Richard Thorpe (an infrequently and never fully seen character, to whom she always refers to with a sneer as "Doctor Dick"). Sometimes we did see the back of his head. I think a couple times we heard him speak.
Stanley Walker from Will and Grace
Her husband, Stanley Walker, is described as an extremely wealthy and overweight man with some unusual sexual tastes, who gives a lot of business to Pizza Hut and Taco Bell. Although Karen often insults Stan and implies she married him for his money, the truth is she was hopelessly devoted and in love with Stan. Sometimes we saw his feet or the back of his head. I am not sure if we heard his voice.
Mrs. Wolowitz from Big Bang Theory
She is voiced by Carol Ann Susi. Howard's overbearing Jewish mother, she is never seen on-screen but her deep voice is heard when he is at their house or when he talks to her on the phone. She talks to Howard always by yelling at him from another room, which results in awkward conversations with Howard yelling back at her.
Dorothy's Brother Phil on Golden Girls
Dorothy has a cross-dressing brother named Phil who has many kids and lives poor and always asking for money from Sophia. We never see him but he does die and we do meet his wife. He is often a running joke.
Jerry's cousin Jeffery in Seinfeld
Jerry's horse-faced cousin, about whom Uncle Leo always raves. Jeffrey once got Jerry tickets to a Paul Simon concert, and a glasses-less George once claimed to see Jeffrey kissing Jerry's girlfriend in the street (it turned out to be a policewoman patting a horse). The back of Cousin Jeffrey's head can be seen in the deleted scenes for the policewoman/horse episode on the season DVD.
In this tokusatsu series produced by DiC in response to Power Rangers and used footage from Japanese series Gridman. Elizabeth was the little sister of the main character who we never saw. Her voice was played by Kath Soucie.