Thrilling forum

Il ratto delle sabine (1961) as Friend of King Titus Tazio (probably one of his military leaders from his costume).

You get quite different shots of Niksa's scenes in the Italian and French prints.

La schiava di Roma (1961) credited as Nicola Stefanini, but hardly seen, as Modius

Sansone (1961) credited as actor (as Nik Stefanini) and as Assistant director (as N. Stefanini).

He maybe appears as one of the Tribal champions who challenge Samson, but his face isn't seen too clearly so it's hard to be certain, so I'm therefore putting it as an uncertain identification. If this isn't Niksa then I'm pretty certain he does not appear as there is no-one else similar looking in the film. He was also credited as actor and assistant director on La furia di Ercole, which was filmed back-to-back with this film and in which he definitely does appear.

Anno 79: La distruzione di Ercolano (1962) credited as Nicola Stefanini, as Valerio

Col ferro e col fuoco (1962) as Andrea.

IMDb says he should be credited as Nicola Stefanini, which he isn't, but there is a credit for "Alberto Stefanini" which I guess must refer to Niksa. Images upgraded

Il capitano di ferro (1962) credited as Nicola Stefanini, as Lieutenant of Di Rauchwitz

Il vecchio testamento (1963), credited as "Nicola Stefanini", as A Maccabee

La furia di Ercole (1962) credited as actor as Nik Stefanini and Assistant director as N. Stefanini, as Robur

La leggenda di Fra Diavolo (1962) Role uncertain

La valle dei lunghi coltelli (Winnetou - 1. Teil) (1963) credited, as Bullock