Tuxedo Mask, also known as Mamoru Chiba, is the lead male character in the Sailor Moon franchise. As Mamoru, he acts as the down-to-earth boyfriend of Usagi. As Tuxedo Mask, he acts as an ally of Sailor Moon (throwing roses and giving heroic chants). On the Moon Kingdom, he was known as Endymion, and is Usagi's future husband. The other Sailor Scouts look up to him as well.
In the original English dub from DiC and Optimum Productions, "Darien" was first voiced by Rino Romano in one of his earlier roles (before going on to voice iconic characters like Spider-Man and Batman). He voiced "Darien"/Tuxedo Mask in only 11 episodes before leaving to pursue other opportunities.
Toby Proctor took over the role in Episode 12, and stayed in the role throughout the rest of the English season, ending at Episode 65 (mid-way through Sailor Moon R).
Vince Corazza took over the role on Episode 66, after previously voicing "Alan". This recast occurred after a two-year hiatus, and Toby Proctor wasn't able to return to the role (it's been reported that he left over a pay dispute). Vince Corazza voiced "Darien" / Tuxedo Mask for the rest of Sailor Moon R, as well as all 3 movies. He later went on to reprise the role for the remaining English seasons: Sailor Moon S and Sailor Moon SuperS, becoming most well-known in the role.
In Sailor Moon Crystal and the uncut redub of the original anime franchise from Viz Media and Studiopolis, Mamoru/Tuxedo Mask is voiced by Robbie Daymond.