Reginald Grey, 3rd Baron Grey de Ruthyn (c. 1362 – September 30, 1440) succeeded to the title on his father Reginald's death in July 1388.

In 1410 after a long dispute the younger Reginald won the right to bear the arms of the Hastings family. He enjoyed the favour both of Richard II and Henry IV, and his chief military exploits were against the Welsh, who took him prisoner in 1402 and only released him upon payment of a heavy ransom.

Grey was a member of the council which governed England during the absence of Henry V in France in 1415; he fought in the French wars in 1420 and 1421.

He married Margaret de Ros, daughter of Thomas de Ros, 5th Baron de Ros. By her he had two children:
• Sir John Grey (c. 1387 – 1439), who predeceased his father, leaving issue
• Margaret Grey (d. aft. May 1426), married William Bonville, 1st Lord Bonville.