There are a number of locations in England that could potentially be sources of the Millington name.
There are also a number of Millington locations in the United States:
Perhaps the most famous Millington, is Gilbert Millington (c. 1597 - 1665/6) who was the MP for Nottingham in the Long Parliament of 1640 and who signed the death warrant of Charles I in 1649. Gilbert's signature can be seen quite clearly in the penultimate column.