Sigmund Mogulesko (16 December 1858 – 4 February 1914) — Yiddish: זעליק מאָגולעסקאָ Zelik Mogulesko, first name also sometimes spelled as Zigmund, Siegmund, Zelig, or Selig, last name sometimes spelled Mogulescu — was a singer, actor, and composer in the Yiddish theater in New York City. He was born in Kalarash, Bessarabia (now Călăraşi in Moldova) and began singing in the local synagogue choir. Before reaching adolescence, he was paid nearly three times what teachers made, to sing in the synagogue of Chişinău. Soon after moving to Bucharest, Romania, he was paid to sing in churches as well as synagogues, and started acting.

He was a star in Abraham Goldfaden's first Bucharest-based theater troupe — and the playwright wrote the title role of Shmendrik for him. Mogulesko soon founded his own troupe and dominated Yiddish theatre in Romania for a decade. After immigrating to the United States, he eventually founded the Rumanian Opera House on New York City's Lower East Side, one of the great venues of Yiddish theater. The Jewish Encyclopedia described him in 1904 as "the best comedian on the Yiddish stage… He is known also as a leading composer of music for the Yiddish stage."