Thomas Ongelibel Remengesau, also known Thomas Remengesau, Senior (born c. 1931) is a politician in Palau. He was Vice President of Palau twice (1985–1988 and 1993–2001), and acting President of Palau twice (1985 and 1988–1989), following the violent deaths of two presidents.
His son Tommy Remengesau was the 6th President of Palau (2001–2009).