Cause of death: cystic fibrosis
Grégory Jean-Paul Lemarchal (13 May 1983 – 30 April 2007), known professionally as Grégory Lemarchal, was a French singer who rose to fame by winning the fourth series of the reality television show Star Academy, which was broadcast on the TF1.
He died at the age of 23 of health complications (cystic fibrosis) while waiting in hospital for a lung transplant. A posthumous album, La Voix d'un ange, was released with profits going towards the Association Grégory Lemarchal charity. A compilation, Rêves, was released in 2009. He has sold more than 2 million albums.
Source : Wikipedia