Ahangama Withanage Oswin Nandimithra Abeyagoonasekera[1] (known as Ossie Abeygunasekera; died 1994) was a member of Parliament and chairman and the leader of the Sri Lanka Mahajana Pakshaya or Party.

He was arrested as a Naxalite prisoner in 1982 along with Vijaya Kumaratunga for printing the "Rice ration book".

In 1986, he negotiated with the LTTE for a peaceful solution of the ethnic conflict and for the release of the Sri Lankan soldiers who were captured.

During the 1989 youth insurrection in Sri Lanka, there were several failed assassination attempts on his life.

[4] Ossie Abeyagunasekera was married with one child, Asanga Abeyagoonasekera, who was the founding director general of the Institute of National Security Studies Sri Lanka.