Mark Viduka (born October 9, 1975 in Melbourne, Australia) is a football (soccer) player of Croatian descent. He is particularly associated with British clubs Celtic, Leeds and Middlesbrough.

Viduka started his career in Australia with Melbourne, before a spell with Croatia Zagreb caught the attention of Celtic - who bought him in December 1998 for £3.5 million.

The Australian international was voted Scottish Premier League Player of the Year after scoring 27 goals in his first full season at Parkhead. He was regarded as a skilled player, able to hold the ball up well and bring other players into the game.

The Leeds United manager David O'Leary swooped for Viduka just before the 1999/2000 season after tracking the big Aussie striker for some time. Leeds paid Celtic £6 million, after Viduka told the Scottish club he wanted a bigger challenge elsewhere.

At Leeds he was expected to line up in a three-pronged attack alongside fellow Aussie Harry Kewell and Michael Bridges, but injuries to those two saw him form a partnership with Alan Smith in Leeds Champions League matches, while Robbie Keane also benefited in their Premiership matches together. In his first Elland Road season, Viduka scored 22 goals, and - committed to Leeds - he signed a new five-year deal in the summer of 2001.

In the 2002/03 campaign Viduka scored another 22 goals, forming a good partnership with Smith and thriving off Kewell's passing ability.

However, Leeds' off-pitch financial troubles prompted the club to sell key players, including Kewell (sold to Liverpool) and Keane (sold to Spurs). This prompted speculation that Viduka would join the Leeds exodus with Barcelona (Spain), confirming their interest in the Australian international along with Premiership clubs Liverpool and Manchester United.

With the relegation of Leeds United to the Football League Championship, the sale of Viduka's contract during the summer of 2004 became all but inevitable. On 8 July, Viduka's transfer to Middlesbrough was completed.