Thrilling forum

As originally suggested by Vecchiaguardia, the film listed as Il mercenario in John Benedy's Killing biography is indeed the same film as La congiura dei dieci (1962) and Benedy can be spotted in a tiny role near the end of the film
The pics aren't very good, but as you can see, the last one is depicting the same scene that is shown in the movie still from the Killing biography

Very early role in La cento chilometri (1959) as Man who lifts up Cesare when he wins the race

Il processo di Verona (1963) as Fascist officer

I was finally able to find the great John Benedy in Rocco e i suoi fratelli (1960) as Boxing match spectator I must thank John Benedy himself, who was kind enough to give me some infos about his little role in the movie.

Photo roman Sensation october (1968) (in French) J'ai perdu mon amour, credited as Sandro
couldn't copy the cover of the magazine, but you see John on the left of the cast list

Photo roman Résistance july (1972) in French, Défi à la mort, seen on the cover as a soldier
He is clearly seen here on the left

Una vita violenta (1962) as Tommaso's friend

Patrick vive ancora (1980) as Peter Suniak Originally posted by vecchiaguardia

Il triangolo rosso (1967 TV series) Season 1, episode 4: "Le due verità", credited as "Gianni De Benedittis", as Truck driver

Strategia per una missione di morte (1979), credited, as Son of the sheik credit shot added; originally posted by Johan