Diego Marcelo Osella (born September 4, 1969) is a retired Argentine professional basketball player.
Osella spent the majority of his career in Argentina with three brief spells in Spain and Italy. He was the Argentine League Finals MVP in 1999, while his featured in 9 Argentine All-Star Games (1989, 1990, 1992, 1993, 1995, 1996, 1997, 1998, 1999).
With the senior Argentine national basketball team, Osella competed at the 1996 Summer Olympic Games in Atlanta, Georgia, where his team finished in ninth place in the overall-rankings. A year earlier, he helped claim Argentina's first ever gold medal in senior men's basketball, at the 1995 Pan American Games, after defeating the United States in the final, in Mar del Plata, Argentina.