William Donald Stewart (born October 6, 1957) is a Canadian-born Italian former professional ice hockey defenceman and former coach.

Stewart was named head coach of the New York Islanders on January 21, 1999, after Mike Milbury himself stepped down to concentrate solely on his GM duties.

The roster that year included the four "Brampton Boys", one of whom, Ryan Barnes, faced charges of assault with a weapon after a stick-swinging incident during a game in October.

Finally, Stewart himself made headlines and was banned from entering the United States for twice smuggling a Ukrainian-born player over the Canada-U.S. border in the baggage compartment of the team bus.

[2] Stewart infamously walked out of the Halifax Metro Centre without conducting any interviews with the media, following Barrie's 6-2 loss to the Rimouski Océanic in the 2000 Memorial Cup championship game.

[3] Following the controversial season in Barrie, Stewart continued his coaching career in Germany, and made headlines during the DEL quarterfinals in 2001 when he was involved in a mass brawl in game three against the Berlin Capitals,[4] during which he hit Capitals' head coach Pavel Gross in the head and Stewart was injured as well.

[5] In the finals against the München Barons, he feigned fainting behind the Adler Mannheim bench to buy his star player Jan Alston time to get his skates sharpened.

"[14] He was sacked as Straubing head coach on October 18, 2017, after his team won only five of the first 13 games of the season and dropped to the very bottom of the DEL standings.