Robert Sedlacek, b. 23 July 1881 in Vienna, died 15 May 1957 in Vienna, was a commercial artist and illustrator. He illustrated the Nesthäkchen books of Else Ury.
Sedlacek trained with Siegmund L'Allemand, 1900-1904, at the Academy of Fine Arts Vienna and became a middle school teacher 1904.
From 1945 to 1952 Sedlacek was a member of the in Vienna. He worked as a graphic artist for industry (including advertisements for 4711 cologne and Persil laundry detergent) and illustrated more than 200 books. He was employed by the publications ' and ' and published his illustrations in Zurich and Vienna. For Meidingers Jugendschriften Verlag Sedlacek illustrated the Nesthäkchen books of Else Ury with colored, full-page glossy images as well as black and white pen drawings. In later editions he changed his illustrations slightly, adapting to the style of the time.