Evan Seys (alternates: Yevan or Ievan) (1604–1685) was an eminent lawyer of his day who rose to national office under Oliver Cromwell as Attorney General, and served as a member of parliament after the Restoration. From c.1649 until his death he was involved in the politics of his native Glamorgan, and of Gloucestershire. He was a committed and active Protestant and an antiquarian scholar.