Željko Mavrović (pronounced [ˈʒěːʎko ˈmɑːvroʋitɕ]; born 17 February 1969) is a Croatian former professional boxer who competed from 1993 to 1998.

In 1998, as an undefeated challenger, he faced Lennox Lewis for the WBC heavyweight title, but lost in what would be his final fight.

In 1998, he went up against Lennox Lewis for the world heavyweight champion title, but lost after twelve rounds via unanimous decision 119–109, 117–112, and 117–111.

[3] Lewis described the fight as the most awkward win of his career, citing sauna-like conditions in the ring, as well as Mavrović's agility, motivation and preparedness.

In the next years, he was a few times scheduled against quality opposition (like for example against Hasim Rahman in 1999 where his late replacement Oleg Maskaev then knocked Rahman out of the ring in a well-remembered fight), but he always had to pull out due to injuries and he ultimately had to finish his career due to an undisclosed illness.