[1] Born Lorenzo Louis (Lou) Degni in Brooklyn, NY, Forest was a third generation Italian-American; his grandparents were from Naples.

Though he did not get the part, he became a member of the musclemen troupe in Mae West's Las Vegas stage show.

[3] After the worldwide success of Hercules, he became the second American actor recruited by Italian producers (after Steve Reeves), and was signed to a three-picture contract with La vendetta di Ercole (retitled Goliath and the Dragon) as his first film for the US market.

At this time Degni began using the pseudonym Mark Forest, and using his advantage of speaking fluent Italian prior to arriving in Europe.

[4] Forest continued in the peplum genre, active in Rome from 1961-1965,[2] leaving the cinema to pursue a career as a European opera singer (tenor), skilled in the bel canto technique, instructed by Giovanni Millo, composer and former tenor of the Metropolitan Opera of New York, father of the lyric soprano Aprile Millo.