Thomas Grey, Lord Grey of Groby, was an elected Member of Parliament for Leicester during the English Long Parliament, an active member of the Parliamentary party and a regicide. He was the eldest son of Henry Grey, 1st Earl of Stamford, using his father's as his own courtesy title, and Anne Cecil, daughter of William Cecil, 2nd Earl of Exeter.

Henry Grey, 1st Earl of Stamford, known as the Lord Grey of Groby from 1614 to 1628, was an English nobleman and military leader. He was the eldest son of Sir John Grey and Elizabeth Nevill. His mother was probably a daughter of Edward Nevill, 8th Baron Bergavenny and his wife Rachel Lennard.