I first encountered Ronet in 1960 as Dickie Greenleaf in one of the first European films I saw back then, Rene Clement's PLEIN SOLEIL, from Highsmith's book which is one of my favourites. Delon had the more showy role, but Ronet captured Greenleaf perfectly. He had already done Malle's LIFT TO THE SCAFFOLD in 1958 (see below) and appeared in other films like CARVE HER NAME WITH PRIDE being in films since the early '50s.
Ronet brought a complexity and depth to his roles, and an easy charm, even when featured as the lover in Chabrol's LA FEMME INFIDELE in 1968 - another one where he gets killed off, coming into close contact with a blunt object. Then there was that fatal re-union with Delon in LA PISCINE, Jacques Deray's glossy thriller from 1969, also with Romy Schneider, whom Ronet starred with in QUI? IN 1970 - a so-so thriller but with good roles for them. He was perfect with Jean Seberg in Chabrol's sunlit comedy thriller THE ROUTE TO CORINTH in 1967, and with Monica Vitti in THE SCARLET LADY in 1969 (as per my reviews on those, Vitti, Seberg, Schneider labels). He also featured in other international movies like Carl Foreman's THE VICTORS in 1963 and the all-star BLOODLINE (with Schneider again) in 1979, and part of Vadim's LA RONDE remake in 1964.
His best role though has to be in Malle's LE FEU FOLLET in 1963 as the recovering alcoholic Alain Leroy who is trying to find a reason to go on living. Its a profound, moving, complex masterwork - reviewed below. Ronet had quite a prolific career (as detailed on his profile at IMDB) and did a lot of routine films, as most actors do, but at his best he was supreme. He died in 1983 aged 55.