"I would never let you not let me protect the President." - To Toby "In the Shadow of Two Gunmen (Part II)"
Butterfield was wounded during the shooting in Virginia, receiving a bullet in his hand. Despite the fact that his hand was bleeding, he refused to be treated for the wound until after President Bartlet had been secured within George Washington Hospital including overriding an earlier order from the President to go to the hospital to look after his hand before they became aware of the President's own injury.
His actions during the assassination attempt are based on real-life Secret Service agent Jerry Parr, who pushed President Ronald Reagan into his limo during an assassination attempt in 1981. Butterfield subsequently ordered the limo to head to GW Hospital after he discovered the President was wounded.
Butterfield subsequently prevented Toby releasing a memo written by the Communications Director which would have shown that the lack of the 'tent' was the result of direct White House instruction, and not any kind of failure on the part of the Secret Service.
He is played by Michael O'Neill.