Thomas J. Gnat (December 2, 1936 - June 21, 2017) was a bishop of the Eastern Diocese of Polish National Catholic Church.

He was born in Milwaukee, Wisconsin and attended Savonarola Theological Seminary in Scranton, Pennsylvania.

In 1970, he was appointed as Administrative Senior for a deanery within the Polish National Catholic Church.

Gnat was elected bishop by the 15th Synod of the Polish National Church, and he was consecrated on November 30, 1978 in the cathedral of St. Saint Stanislaus in Scranton.

After his episcopal ordination, he was the Bishop Ordinary of the Eastern Diocese of the Polish National Catholic Church from 1978 to his retirement in 2011.