Thomas, Lord Grey of Groby (c. 1623–1657), was the Member of Parliament for Leicester during the English Long Parliament, and an active member of the Parliamentary party. He was the eldest son of Henry Grey, 1st Earl of Stamford,

In January 1643 he was appointed commander-in-chief of the forces of the Parliament in the Midland Counties and Governor of Leicester. In 1648 he won some credit for his share in the pursuit and capture of the Duke of Hamilton; he assisted Colonel Pride to purge the House of Commons later in the same year; and he was a member of the court which tried the king, whose death-warrant he signed.

A member of the Council of State under the Commonwealth, Grey fought against the Scots in 1651, and in February 1655 he was arrested on suspicion of conspiring against Cromwell. He was, however, soon released, but he predeceased his father in April or May 1657. His only son succeeded as Thomas Grey, 2nd Earl of Stamford.