Deborah Fiderer is a character in the NBC television series The West Wing. She is portrayed by noted actor and comedian Lily Tomlin. The character first appeared during the program's third season and remained until its finale.

After the death of President Josiah Bartlet's previous private secretary Mrs. Landingham, Bartlet was extremely reluctant to come to terms with her death fully by hiring a permanent replacement. Finally prevailed upon to do so by the White House staff, most of the proposed candidates did not meet with the President's approval. Although they were all highly qualified, they lacked the character and sense of humour that the President was looking for. In contrast, Fiderer was opinionated, strong willed, perhaps eccentric and in any case very much her own woman. During the interview with President Bartlet, Deborah revealed that she came to the White House somewhat "high" and that she had previously been an Alpaca farmer. Later, at a poker game with the senior White House staff, she cleaned out the other players by routinely betting $50 on each hand. Along with the First Lady, she is perhaps the character most concerned about preventing the President from being overworked in the light of his multiple sclerosis, to the point of having new telephone functions installed so that she could better respond to and log his calls.

She was previously Debbie DiLaguardia, and worked for the White House personnel office, mentioned in dialogue in the first season episode "A Proportional Response" as recommending Charlie Young to serve as the President's personal assistant. However, she passed over David Dweck, the son of a powerful Democratic Party contributor, an action for which she was fired from her previous position.

She says that she admires Harry S Truman.