Housley, a 39-year-old defenseman, was sent to the Maple Leafs for fourth- and ninth-round picks in the 2003 draft, while Thomas, a 39-year-old winger, was shipped to Anaheim for a fifth-round pick.
Chicago also got future considerations from the Philadelphia Flyers for center Peter White, whose father-in-law, Bob Clarke, is the Flyers' general manager.
Housley is a puck-carrying defenseman who will play the point on the Maple Leafs' power play. The all-time leading scorer among American-born players in NHL history has 338 goals and 894 assists in 1,494 games.
Ray Bourque, Paul Coffey, and Al MacInnis are the only defensemen in NHL history with more points than Housley, who has six goals and 23 assists in 57 games this season. He has missed the last 11 games because of a broken foot.
Housley is the second veteran defenseman acquired by Toronto in three days. The Maple Leafs landed Glen Wesley from Carolina on Sunday for a 2004 second-round draft pick.
Thomas has just four goals and 13 assists in 69 games this season, but scored his 400th career goal against Colorado's Patrick Roy on Feb. 17, and brings much-needed postseason experience to the Ducks, who are closing in on the third playoff berth in team history.
Nicknamed "Stumpy," Thomas has 401 goals, 497 assists, and 1,279 penalty minutes in 1,179 games with Toronto, Chicago, the New York Islanders, and New Jersey. No one on the Anaheim roster has appeared in more playoff games than Thomas, who has 50 goals and 48 assists in 147 postseason contests.
White returns to Philadelphia, where he had 10 goals and 21 assists in 101 games over three seasons. He also has played for Edmonton and Toronto, but spent most of this season with Norfolk of the American Hockey League, picking up 17 goals and 26 assists in 47 games.