Betsy Halpert is the mother of Jim, Pete, Tom and Larisa Halpert. She is married to Gerald Halpert. She can be seen in several episodes, including the ones below. She is portrayed by Perry Smith.
In "Frame Toby", Jim purchases her and Gerald's house, where he grew up, for him and Pam to live in.
In Stress Relief, after Pam's parents (Helene and William) divorce, Jim jokes that 50% of relationships end badly, and that he is lucky that Pam's parents were divorcing, not his.
In Niagara, at Jim and Pam's wedding, Betsy can be seen talking to Jim, Pam, and Michael; Jim introduces her to Michael. Later on in the episode, Betsy can be seen in the actual wedding ceremony.
In Christening, Betsy can be seen at Cece's christening ceremony.