PRINCETON, N.J. (AP) _ Muriel Gardiner Buttinger, an author and psychiatrist who was active in the anti-Fascist movement in Austria during the 1930s, died Wednesday. She was 83.

Many people believe she was the model for Julia, the character in Lillian Hellman's book, ''Pentimento,'' although the writer denied that before her death. A film titled ''Julia'' starred Jane Fonda and Vanessa Redgrave.

Like Julia, Mrs. Buttinger, who lived in Pennington for 45 years before moving to Hightstown last month, was a wealthy American who studied at Oxford and the University of Vienna Medical School and were involved in the anti-Nazi resistance in the '30s.

She later married Joseph Buttinger, leader of the Austrian Revolutionary Socialists, and offered her home to fleeing dissidents, provided them with affidavits and transported false passports taped to her body for those leaving Austria, according to her book, ''Code Name 'Mary,''' one of several she wrote.

Mrs. Buttinger was a driving force behind the creation of the Freud Museum in Hempstead, England, expected to open in early 1986. She also was instrumental in founding the Center for Advanced Psychoanalytic Studies.

She is survived by her husband, a daughter, six grandchildren and a sister. No services were announced.