Betty Riker was the wife of Kyle Riker, and the mother of William T. Riker. (TNG: "Conundrum") She died suddenly in 2337, when Will was only two years old. (TNG: "Interface")
One of Betty's final requests was that Kyle raise Will in Valdez, which he did. Betty's death was very traumatic for Kyle and the only thing which kept him going was Will, although he did not reveal this fact to his son. The memories of Betty's presence at their Alaska home were painful for both, and this initial trauma created a rift between the two Rikers which would last thirty years. (TNG: "The Icarus Factor")
When Will first started school, he began to craft stories about his mother as if she were still alive. Eventually, he told the stories about her so often, he began to believe them. Soon, his teacher learned of this problem, and both she and Kyle had to talk to Will and make him realize that his mother was dead and she was not coming back. Will cried the entire night following, but later realized it was an important step in accepting his mother's death. (TNG: "Interface")
- Betty Riker's name was never spoken in dialog, but was established in a biography screen prepared for Will in "Conundrum," although it was not seen in the episode. "The Icarus Factor" implies the cause of her death was sudden, and may have been due to an illness.