Aden Abdulle Osman Da’ar, 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.

The Somali Republic was formed by the union of the Trust Territory of Somaliland and the State of Somaliland. A government was formed by Abdullahi Issa Mohamud and Muhammad Haji Ibrahim Egal and other members of the trusteeship and protectorate administrations, with Haji Bashir Ismail Yusuf as President of the Somali National Assembly and Aden Abdullah Osman Daar as President of the Somali Republic. On 22 July 1960, Daar appointed Abdirashid Ali Shermarke as Prime Minister. On 20 July 1961 and through a popular referendum, Somalia ratified a new constitution, which was first drafted in 1960. The new constitution was rejected by Somaliland.