Mikas Petrauskas (1873–1937) was a Lithuanian composer and choirmaster best known as the author of the first Lithuanian opera Birutė (1906). He was an elder brother of the singer Kipras Petrauskas.

Petrauskas learned to play church organ from his father and began working as an organist at the age of 15. He worked in Labanoras, Obeliai, and Hierviaty before enrolling at the Saint Petersburg Conservatory in 1901. As a student, he wrote and staged the first Lithuanian operettas. In 1905, he moved to Vilnius where he became leader of the choir of Kanklės of Vilnius Society and staged his opera Birutė in 1906. Trouble with the Tsarist police forced him to leave the Russian Empire first for Switzerland and then for the United States. There he organized various concerts and theater performances, opened a music school, and established and led choirs and other performing groups among Lithuanian Americans. He organized and led Birutė choir in Chicago and Gabija choir in Boston. Both choirs continued to perform until 1950s. His music school operated from 1910 to 1924 and had up to 130 students per year. By his own estimate, during the first 17 years in the United States, he taught music and singing to some 4,000 people. He returned to Lithuania in 1930 and died in 1937.

Petrauskas works include two operas, 19 operettas, and about 200 songs.