Aden Abdulle Osman Da’ar (Somali: Aadan Cabdulle Cismaan Dacar, Arabic: آدم عبد الله عثمان دعر) (9 December 1908 – 8 June 2007), popularly known as Aden Adde, was a Somali politician who served as the first president of the Somali Republic from 1 July 1960 to 6 July 1967. He had previously served in the Somali Youth League in 1944.
In 1946, he was named Secretary of the party's section in Beledweyne, Somali Republic. In 1951, the Mudug Regional Council appointed him for the Regional Council, and two years later, he became Vice President of the Regional Council. From 1954 until 1956, he was the President of the Somali Youth League. He was re-elected in May 1958, and he continued to hold this position simultaneously along with that of Speaker of the Legislative Assembly until 1960.