Grettel Barboza (born September 6, 1956 in San José) is a Costa Rican sport shooter.
She has been selected to compete for Costa Rica at the 2004 Summer Olympics, finishing thirty-fifth in the air pistol.Barboza qualified as the 47-year-old lone shooter for the Costa Rican squad in the women's 10 m air pistol at the 2004 Summer Olympics in Athens.
She had been granted an Olympic invitation for her country by ISSF and IOC, having registered a minimum qualifying score of 367 at the ISSF World Cup meet in Atlanta, Georgia, United States three years earlier.
Barboza fired a lowly 368 out of a possible 400 to force a three-way tie with fellow Latin American markswomen Amanda Mondol of Colombia and triple Olympian Margarita Tarradell of Cuba for thirty-fifth place in the qualifying round, failing to advance further to the final.