Ellen Bernard (née Dorset) is the mother of Andy Bernard. She, like her husband Walter Sr., is somewhat cold to Andy and more loving toward her favorite son, Walter Jr. There was a change in character after her first appearance.
Ellen was present along with Walter Bernard to happily witness Andy's proposal to Angela (Goodbye Toby).
When constantly being mocked by the office staff for his ancestors having made their money off slaves, Andy calls his mother to prove them wrong. He does in fact prove that his ancestors did not own slaves however his mother tells him that the Bernards made their money by transporting them causing Andy more humiliation (Andy's Ancestry).
Andy calls his mother to see if they could make a donation to Andy's old a cappella group Here Comes Treble so that Andy can support the current group. He is disturbed to learn that his family is in fact broke (Here Comes Treble).
In order to get his mother health insurance and to allow her to have enough money so that she won't have to work, Andy is forced to sell the family boat (The Boat).