(written from a Production point of view)
Agostino Castagnola is an opera singer, a tenor, who worked as voice double for Robert Picardo in the Star Trek: Voyager sixth season episode "Virtuoso". He performed the opera pieces Dio, che nell'alma infondere and Rondine al nido in this episode. 
Born in San Pedro, California, Castagnola attended the San Pedro Senior High School and the University of Southern California. Beside working as studio singer, he also performed at the Los Angeles Opera. Here, he performed in versions of Madame Butterfly (1986), Otello (1986), Macbeth (1987), Cosi fan tutte (1988), Orpheus in the Underworld (1989), Barber of Seville (1991), La Boheme (1993), Don Pasquale (1995), The Magic Flute (1998), and Lohengrin (2001). Today he has been working at the Mary Star of the Sea High School in San Pedro.
Castagnola lent his voice to other productions including episodes of Muppets Tonight (1997, supervising produced by Kirk R. Thatcher), Dexter's Laboratory (1998, with Frank Welker), Family Guy (2009, created by and starring Seth MacFarlane), and as singing voice of Captain James T. Kirk and Pavel Chekov in the Robot Chicken episode "Two Weeks Without Food" (2009).
As an actor, Castelagno appeared in episodes of Dharma & Greg (1999, with Mitchell Ryan and Vincent Schiavelli), Providence, the 2001 Academy Awards, Just Shoot Me! (2003, with Patrick Fabian and Simon Templeman),  and Malcolm in the Middle (2006). He also performed on the soundtrack of the animated movie Mickey, Donald, Goofy: The Three Musketeers (2004) and on the animated series Lunatics Unleashed (2005).