Joseph Hewitt (1754–1794) was an English-born barrister, politician and judge in late eighteenth-century Ireland.
He was born in Coventry, the third son of James Hewitt, 1st Viscount Lifford and his first wife Mary Rhys Williams, who died in 1765.
His father's eminence as a judge may have influenced Joseph's decision to pursue a legal career.
He entered the Middle Temple in 1768 and was called to the Irish Bar in 1776.
He became a justice of the Court of King's Bench (Ireland) in 1791, but his health had always been bad, and he died only three years later, at the early age of 40.