Robert J. Mellow is an American politician from Pennsylvania who served as a Democratic member of the Pennsylvania State Senate for the 22nd District from 1971 to 2010. He also served as the Minority Floor Leader from 1994 to 2010 and President pro tempore from 1992 to 1994. In 2012, he pleaded guilty to federal charges of conspiracy to commit mail fraud and filing a false tax return and was sentenced to 16 months in federal prison.