Success on TV can expand a performer's reputation, but it can also obscure her accomplishments. Charlotte Rae is best known as a sitcomedienne from her long stint on NBC's warm and fuzzy The Facts of Life, as well as for her supporting roles on Sesame Street, Hot L Baltimore, and Car 54, Where Are You? But she's also a singer and stage actress of great distinction. Her knack for eccentric comedy made her a magnificent Mrs. Peachum in the legendary 1954 off-Broadway revival of The Threepenny Opera, in the past few years, she has reveled in the ferocious dark humor of Beckett's Happy Days at LA's Mark Taper Forum and in the tart feistiness of Driving Miss Daisy at the Briar Street Theatre here. An alumna of Northwestern University and its Waa-Mu variety shows, the Milwaukee-bred artist returns to her alma mater with this evening of songs, character sketches, and anecdotes (illustrated with slides) tracing her long and delightful career. The program, which has already played both coasts, features novelty tunes written especially for her by her old Waa-Mu colleague Sheldon (Fiddler on the Roof) Harnick, who encouraged her to come to New York in 1948 because there was no one around who could do what she did. There still isn't. The admittedly pricey event is a benefit for Northwestern's Theatre and Interpretation Center State of the Art Fund; tickets include a postshow party with Rae. Josephine Louis Theatre, 1979 South Campus Dr., Evanston, 708-491-7282. Saturday, March 12, 8 PM. $100.