Kazimierz Krukowski (2 February 1901 in Łódź – 24 December 1984 in Warsaw), professionally known as Lopek, was a Polish cabaret performer and writer, revue and film actor.

He performed songs and monologues by famous poets and songwriters including Marian Hemar, Jerzy Jurandot, Antoni Słonimski, Julian Tuwim and Andrzej Włast.

He made his first movie in 1927 (Ziemia obiecana) as part of a comedy duo, "Lopek and Florek," with Adolf Dymsza; they made several more movies together including Janko Muzykant; Ułani, ułani, chłopcy malowani, and Co mój mąż robi w nocy?

He fought in the Soviet Union and subsequently lived in Britain, the United States, and Argentina, where he ran the El Nacional theater.

He wrote several books: Mała antologia kabaretu (Small cabaret anthology), Z Melpomeną na emigracji (With Melpomene in exile) and Moja Warszawka (My Warsaw).