Father Thadeus Nguyễn Văn Lý (born May 15, 1946) is a Vietnamese Roman Catholic priest and dissident.
He was involved in many pro-democracy movements for which he was imprisoned for a total of almost 15 years. For his ongoing imprisonment and continuous non-violent protest, Amnesty International adopted Father Lý in December 1983 as a prisoner of conscience. Most recently, his support for the Bloc 8406 manifesto has led to his sentence on March 30, 2007, for an additional eight years in prison, where he was released and then returned in 2011.