Michael Klim OAM (born August 13, 1977 in Gdynia) is a Polish-bornAustralian swimmer.

Klim was first selected to represent Australia in the Commonwealth Games in Victoria, Canada in 1994, while still a student at Wesley College, Melbourne. In 1996, he arrived at the Atlanta Olympics ranked first in the world for the 200 m freestyle, but was surprisingly eliminated in the heats. He rebounded to qualify for a finals position in the 100 m butterfly, and swam the freestyle leg in the 4×100 m medley relay, in which Australia claimed a bronze medal.

1998 was Michael Klim's year in the sun. In January, the World Championships were held in Perth, and in front of a boisterous home crowd, he was the leading swimmer of the meet. He triumphed in the 200 m freestyle and the 100 m butterfly, and added silver in the 100 m freestyle, and 50 m freestyle. He was a member of each of Australia's three relay teams, winning gold in the 4×200 m freestyle relay and 4×100 m medley relay, and a silver in the 4×100 m freestyle relay. For his achievements he was named the swimmer of the year by SwimmingWorld magazine.

In 1999, he set a world record in the 100 m butterfly, in a FINA sanctioned time trial (51.81 s). It was broken at the 2003 World Championships in Barcelona by the Ukrainian Andriy Serdinov in the first semifinal of the 100 m butterfly, and then broken another time in the next semifinal by Michael Phelps.

In 2000, at the Sydney Olympics, Klim set a world record (48:18) leading off the 4×100 m freestyle relay, which paved the way for a world record (3:13.67). Three days later, he was part of the 4×200 m freestyle relay, which set another world record (7:07.05), which left the opposition over 5 seconds in arrears on its way to victory. He entered the 100 m freestyle as the world record holder, but his feats in the relay left him fatigued, coming home in 4th place, behind Dutchman Pieter van den Hoogenband, who claimed the world record (47.84) in a semifinal. Again in the 100 m butterfly, he was the world record holder, but was cut down in the closing stages by Sweden's Lars Frölander, finishing second. He also claimed silver as part of the 4×100 m medley relay team.

In 2001, hampered by an ankle injury, Klim was restricted to relay duties, and contributed to another world record, winning gold in the 4×200 m relay (7:04.66). He also collected a gold medal in the 4×100 m freestyle relay.

In 2002 and 2003, he did not compete, due to chronic back and shoulder problems.

In 2004, at the Athens Olympics, he returned to relay duties, collecting a silver in the 4×200 m relay.

In 2005, he swam at the World Championships in Montreal, in the 100 m freestyle, returning to individual action, but failed to progress past the semifinals. He won bronze as part of the 4×100 m freestyle relay.

He is married to Balinese princess and former model, Lindy Rama, who grew up in Tasmania. She gave birth to their first child, daughter Stella, in early 2006, the couple marrying shortly thereafter.

On 26 June 2007 Klim announced his retirement from swimming.