Susan Walker Hammer (December 21, 1938 – March 7, 2020) was an American politician and member of the Democratic Party, who served as the mayor of San Jose, California, from 1991 to 1999. She was voted best local politician six times. Previous to serving as mayor, she represented San Jose City Council District Three, which encompassed the downtown area of the city, from 1983 to 1991.

Hammer was born in Altadena, California, on December 21, 1938. She attended the University of California, Berkeley. She was married to San Jose attorney Philip Hammer, and had three children and six grandchildren. She was diagnosed with Alzheimer's disease in her later years, and it progressed rapidly over the last several months of her life, leading to her death on March 7, 2020.