Thiais is a commune in the southern suburbs of Paris, France. It is located 10.3 km (6.4 mi) from the center of Paris.
The name Thiais comes from Medieval Latin Theodasium or Theodaxium, meaning "estate of Theodasius", a Gallo-Roman landowner.
The Austrian writer Joseph Roth, exiled due to his opposition to the Nazi regime, lived at Thiais at the end of the 1930s and is buried at the local cemetery. The tomb of Russian writer Yevgeny Zamyatin is also there.