Thrilling forum

The Fall of the Roman Empire (1964) as Gladiator trainer.

The image is a little soft (and this from the blu-ray so unlikely to get much sharper), but from the features and the way he stands I think this must be Mario at front right, with the Messinas, in the only scene from the film shot in Italy.

El desperado (1967) as Man who provokes Steve in the saloon

Saffo - Venere di Lesbo (1960) as Soldier

Giulio Cesare, il conquistatore delle Gallie (1962) as Right hand man to Vecingetorix

Very hard to be sure, but the profile and features hidden beneath the wig and false beard seem to match (concurred by Johan). Images upgraded

Colpo maestro al servizio di Sua Maestà britannica (1967) as Film producer

Le meravigliose avventure di Guerrin Meschino (1952) as The giant.

Hard to be sure of this one, the facial features look like it may well be Mario and it certainly is not Alberto Plebani, who is credited playing the role on IMDb, but with the combination of the heavy make-up and fairly soft image added to the fact that it is some years earlier than his current earliest-known role then this has to be an uncertain identification, at least until a sharper print appears.

Ester e il Re (Esther and the King) (1960) as Gladiator (front right)

I normanni (1962) hidden under a wig and false beard once again, as English naval captain.

Nato per uccidere (1967) as Leader of Dodgett henchmen

Agguato sul Bosforo (1969) as Brawler Identification by Nick