Eoin David Ryan (12 June 1920 – 14 December 2001) was an Irish Fianna Fáil politician, and a Senator for thirty years.
Ryan was born in Dublin. When Ryan was born, his father and mother were actively engaged in the War of Independence. His mother Máirín Cregan was arrested when he was a baby in February 1921 and held in prison for a short time at the same time as his father. She later made her name as a writer. His father, James Ryan, was a founder member of Fianna Fáil and a member of successive governments. Eoin Ryan was educated at Presentation College, Bray, and later at Mount St. Joseph Abbey, Roscrea. He joined the Defence Forces during the emergency years of World War II and rose to the rank of captain between 1940 and 1943. For four of his years in the upper house, 1965 to 1969, his father was also a Senator serving after his retirement from the Dáil. He was Leader of the Seanad from 1977 to 1981 and leader of the Fianna Fáil group from 1973 to 1977.