Stéphane Diagana (born 23 July 1969 in Saint-Affrique, Aveyron) is a retired, French track and field sprinter and hurdler. His specialities were the 400 metres hurdles and the 4 x 400 metres relay.
Diagna won the 400 metres hurdles gold medal at the 1997 World Championships in Athens and the 4 x 400 metres relay gold medal at the 2003 World Championships in Paris. In 2002 he won the 400 metres hurdles gold medal at the European Championships in Munich. Diagana also set a new, European 400 metres hurdles outdoor record of 47.37 sec. in Lausanne, Switzerland on 5 July 1995. As of 1 September 2014, this European record still stands.
In his only Olympic appearance, Diagana finished in fourth position in the final of the 400 metres hurdles of the 1992 Olympics in Barcelona. In that Olympics, his 4 x 400 metres relay team was eliminated in the heats.