Mira "Marko" Debelak-Deržaj (26 December 1904 – 27 September 1948) was a Slovenian alpinist, skier, and journalist.

She was born as Mira (also Miroslava Marija Štefanija) in Sarajevo in 1904, as the youngest of four children in her family.

In an arranged marriage, she married Božo Pibernik, from whom she separated and changed her surname back to Debelak in 1933.

Her mountaintop career was also marked by a poor relationship with Pavla Jesih and a serious accident by a fellow climber: Edo Deržaj on the Triglav Wall in 1927.

In 1936, together with Fanny Susan Copeland, she published A Short Guide to the Slovenian Alps (Yugoslavia) for British and American Tourists.