Peter J. Halat Jr. (born July 27, 1942) is an American politician and lawyer who served as the twelfth mayor of Biloxi, Mississippi, and was later convicted and served time for his involvement in a criminal conspiracy which led to the 1987 murders of Halat's former law partner, Mississippi judge Vincent Sherry, and Sherry's wife Margaret, a Biloxi city councilwoman. He was found guilty and sentenced to 18 years in prison, of which he served 15.

Halat was elected mayor in 1989, and likely damaged by allegations as well as testimony in a previous 1991 federal trial involving the criminal conspiracy leading to the Sherry murders, lost a re-election bid in a three-way race in 1993 by just 17 votes out of 8,564 total cast following the posting of the final tally. The FBI investigation eventually ended the city's long tolerance for wide open, illegal gambling and striptease clubs with exorbitantly priced drinks, the purchase of which served as a front for prostitution.