Maris Crane is Niles Crane's wife for the early seasons of the show, though she is never fully seen onscreen. She is the most notable of the show's never-seen characters, and often the subject of many jokes. Her maiden name, and the name of the wealthy family from whom she comes, is not revealed on the series. Maris is immensely wealthy—much wealthier than Niles—spoiled, dominating and neurotic. Many of the characters pointedly dislike her (to Niles' consternation) with Frasier commenting in the show's first episode, "Maris is like the sun...except without the warmth."
Maris makes only two onscreen "appearances"; once in the episode "Voyage of the Damned" where her shadow is seen through a shower curtain, and again in "Rooms with a View" where she appears in Niles' memory, almost completely covered by bandages after surgery. She is described as small, very pale and pathologically emaciated. In The Seal Who Came to Dinner, the pass-code to Maris's seaside home is described as her "ideal weight" and "what she weighed at her débutante ball." during her pageant years. The series of numbers that Niles punched in would mean that Maris, at that time, was either 65 lbs. or 56 lbs, depending on the order of the digits on the key-pad. Aside from her low weight, Maris is subject to various medical problems: she has abnormally tight quadriceps, a rigid spine, a large number of very specific allergies, and cannot produce saliva. She frequently travels to Europe for plastic surgery and expensive health treatments. In a humorous vein, David Hyde Pierce (who portrays Niles) passively describes Maris during a Montreal comedy performance (which he performs in character) as "...a wife who's like a refugee from '[The] Taming of the Shrew'..." 
Maris was born in 1952 in Seattle. Her father was known as "The Commodore" and she also has at least two sisters. As a child Maris was quite chubby, but then she started losing weight and was soon very skinny. She stole a crucifix from the Vatican when she was young. She has a sister named Brie, who was born with only one nostril; she is mentioned as Frasier's date in one episode.
Maris lived in her family's mansion, which has been in the family for four generations after they made their fortune from urinal cakes (although she fooled everyone by telling them her fortune comes from timber). She met her husband, Niles Crane, during an internship in Seattle when he stopped to help her as she was banging on the electric gates to her home. They got married three years later, in 1986.
In 1993 Maris and Niles help Frasier hire Daphne Moon, Niles' future wife. Two years later, she goes to New York without telling Niles, causing him to worry. This causes her to throw him out of the house when he stands up to her, and they stay separated for two years. Maris has an affair with their marital therapist, Dr Bernard Shenkman, in 1998, which causes Niles to finally divorce her.
In 2003 Maris gets involved with an Argentinian polo player, Esteban de Rojo, who is violent. Maris kills Esteban in self defense and stays in jail for a few months. In early 2004 her defense trial is due to take place, but she escapes to her family's private island, from which she cannot be extradited, effectively stranding her for life.