William Ross is a character who was introduced in the Star Trek: Deep Space Nine episode "A Time to Stand".
He was portrayed by the late Barry Jenner.
Born in the 2310s, Ross had a long career in Starfleet, and was an Admiral by the 2370s. Along with Captain Benjamin Sisko Ross was one of the main Starfleet leaders in the war against the The Dominion. After the Federation, Klingons, Romulans, and Cardassians defeated the Dominion Ross joined Sisko and Martok in the halls of Cardassian Central Command for a drink, but seeing the genocide the Dominion had wrought against the Cardassians he lost his desire to have the drink. Ross later represented the Federation at the Dominion's surrender, and gave a brief speech after the Female Changeling signed the peace treaty.
Having spent a great deal of time at DS9 Ross became friends with Sisko as well as Morn.
At some point in his career he became a Section 31 agent. Control/Uraei arranged for Ross to become the main organic leader of the organization. When he and several other Admirals along with Captain Picard forced Federation President Min Zife to leave office, Ross helped arrange Zife's assassination by 31 agents. Ross was forced into retirement by President Bacco when she learned of his role in forcing Zife's removal (but did not learn of his assassination at the time).
In 2387, Uraei was finally deleted due to the efforts of Julian Bashir, Data, Lal, and a Trill journalist. After over 200 years of activity Section 31 was finally exposed to the public. Ross's role in Section 31, including assassinating President Zife was exposed to the public. The Federation Security Agency quickly arrested Ross on Caldos II.
Ross was taken back to the FSA detention facility on Earth, where he and his attorney was murdered by a vengeful FSA officer whose husband had died at the hands of Section 31 a few months earlier.