William Eisen was a communications officer when the TCS Victory was commissioned. He steadily rose in the ranks to eventually become her captain. Near the end of the Kilrathi War, he was assigned Christopher "Maverick" Blair
to be his new wing commander. Under Eisen's command, the pilots of the Victory launched a sneak attack on the Kilrathi homeworld and brought an abrupt end to the war.
After the war, the Liberty was decommissioned, and Eisen was assigned to the TCS Lexington, where he once again crossed paths with Blair, this time investigating alleged terrorist attacks by the Union of Border Worlds. After his investigations lead him to some surprising revelations, he is relieved of command of the Lexington by Captain Hugh Paulsen and forced to flee to the Border Worlds Carrier BWS Intrepid, followed by Blair and several other pilots from the Lexington. He arrives to find a badly damaged ship in need of a captain, and he is promptly elected to be the Intrepid's new captain. He shortly gives command of the Intrepid to Blair and returns to Confederation space to try to uncover the truth behind the events in the Border Worlds.
The last known ship Eisen commanded was the Vesuvius class heavy carrier Mt. St. Helens, which he hijacked along with a skeleton crew to come to the aid of the Intrepid at the culmination of the Border World Conflict.
Eisen has a ship named after him in Wing Commander: Prophecy
: The Vesuvius class heavy carrier TCS Eisen. Eisen is portrayed by the late Jason Bernard, who died of a heart attack in 1996.