Born on December 19, Mary Ellen Harper is the oldest of Carl and Thelma Harper's three children. Even as a child, her snobbish tendencies asserted themselves. she prefers not to associate with anyone in her family—-unless it benefits her in some way. She was married to an often spoken of but never seen husband named Bruce Jackson, whom she later divorced. Her ability to do anything well irritated her resentful younger sister, Eunice Higgins, to no end. This, added to the fact that Ellen was Thelma's clear favorite, added to the explosive rivalry between the two sisters. Ellen later learned of Bruce's infidelity from Eunice, who gleefully exposed it to her face. Ellen's relationship with her brother, Vinton Harper, tends to be amicable, although like the rest of the family, she usually dismisses him for being a bit dim.
Shortly after her divorce from Bruce Jackson, Ellen began to date a man much younger than she named Glen, to which Thelma vehemently objected. She later began seeing Alvin Tutweiler, mayor of Raytown and Ellen's ticket back into the high society that she missed since her divorce. When confronted on this conniving by her mother, she flippantly replied: "it worked for Nancy Reagan."
When the show went into syndication, it was presumed that Ellen still lived in Raytown, but she wasn't seen much after the second season (Betty White was, by this time, starring in The Golden Girls.)
Despite being her mother's favorite, Ellen (like her siblings) isn't spared Thelma's criticism, insults or wrath. When she failed to attend her aunt Fran's funeral, this caused a huge riff in Thelma and Ellen's relationship, and Thelma threatened to not speak to her again. Afterwards, Ellen made an attempt to mend fences with her mother by showing up with a peace offering, but Thelma remained unmoved and ordered her out of the house. Thelma let go of her animosity when she soon after learned that Ellen had been checked into the hospital for surgery (in reality, she had a mere fanny tuck). It was there that Thelma admitted to Ellen that she had always favored her the best of her three kids.
Ellen was chosen as Raytown Country Club's Woman of the Year, and was embarrassed when Thelma, Vint, and Naomi showed up at the awards ceremony. She has also dated a successful businessman named Glenn, who was so young that Thelma observed "She's old enough to have lived two of his lives."
However, in "The Family" sketches on the Carol Burnett Show, Ellen has no qualms about snapping back at her mother, when she is annoyed with her. In those sketches, she was also near gleeful whenever she got something that Eunice wanted, like a Tiffany lampshade, or a box of fine china.
In the television series, it is implied that Thelma was in her late teens when she was born. Evidence of this can be that Ellen is about fifty while her mother is still in her sixties. Also, a flashback shows that when Thelma turns thirty years old, Ellen is already about eleven or twelve years old, showing an eighteen/ninteen year difference in the two's ages.