Leszek Miller (born 3 July 1946) was Prime Minister of Poland from September 2001 to May 2, 2004.

Miller was born in Zyrardow in central Poland. He joined the ruling Polish United Workers' Party party in 1969. Until 1970 he worked as an electrician in a linen textile factory in Zyrardow. In 1977 he graduated from a Higher School of Political Sciences (Wyzsza Szkola Nauk Spolecznych ). From to 1977-1982 he worked in the Regional Committee of PUWP in Skierniewice. In 1988 he became secretary of PUWP at voivodship level, and the following year he was briefly a member of the party's Politburo.

After the dissolution of the communist party, from 1989 to 1993 Miller was secretary-general of SdRP . He became a member of the Sejm in 1991. He was Minister of Labor in Waldemar Pawlak's government, and Minister of Internal Affairs in the governments of Jozef Oleksy and Wlodzimierz Cimoszewicz. He became SLD party leader in December 1999 and served in this position until March 2004. He became Prime Minister of Poland in September 2001. On March 26, 2004, he announced his resignation as prime minister, effective May 2 (the day after Poland became a member of European Union).

His government encountered problems and unpopularity because of high unemployment, possible spending cuts, corruption scandals (most notably the Lew Rywin affair), and Miller's support for U.S. president George W. Bush, particularly the American-led war against Iraq in 2003. In April 2004, Miller's former treasury minister Wieslaw Kaczmarek (now in a splinter socialist party called Socjaldemokracja Polska) accused him of illegally using counter-intelligence services for political reasons. Those allegations are currently being investigated by a special House Inquiry Commission (PKN Orlen investigation commission). A survey conducted in April 2004 found that 92% of Poles had an unfavorable opinion of Miller's government.

Miller's government involved Polish troops in the invasion and occupation of Iraq. The government also completed the negotiations for Poland to join the European Union.