Charles St. Clair Trainor (December 8, 1901 – June 19, 1978) was a lawyer, judge and political figure on Prince Edward Island. He represented 5th Queens in the Legislative Assembly of Prince Edward Island from 1935 to 1939 as a Liberal. He was born in Albany, Prince Edward Island, the son of Thomas Trainor and Annie Greenan, and was educated at Saint Dunstan's College. Trainor articled in law with Mark MacGuigan and was called to the bar in 1927, entering practice with MacGuigan. In 1938, he was named King's Counsel. He was prosecutor for Queens County from 1939 to 1942.