Julia Olehivna Vakulenko (Ukrainian: Юлія Оле́гівна Вакуленко; born 10 July 1983) is a Ukrainian-born Spanish former tennis player. She achieved her career-high singles ranking of world No. 32 in November 2007. Vakulenko reached one WTA Tour final and won seven ITF singles titles.
Having entered the tournament as a qualifier, she defeated then world No. 4 Kim Clijsters in the second round of 2007 J&S Cup in Warsaw, Poland. Vakulenko retired due to injury while trailing by a set and a break of serve in her quarterfinal with fellow Ukrainian player Alona Bondarenko. A week later at the 2007 German Open in Berlin, Vakulenko defeated world No. 3 Amélie Mauresmo and world No. 10 Dinara Safina, both in three sets, on the same day after rain stoppages had caused havoc with the event's schedule. She retired in the first set of her semifinal match against 12th seed and eventual champion Ana Ivanovic due to a hand injury.
On 28 August 2007, in the first round of the US Open, Vakulenko defeated ninth seed Daniela Hantuchová in three sets. She eventually reached the fourth round, her best performance at a major, before falling to Ágnes Szávay.
Seeded third at the final event of the 2007 season, the Bell Challenge in Quebec City, Canada, Vakulenko reached the first WTA Tour final of her career. En route, she defeated Rossana de los Ríos, wildcard entrant Stéphanie Dubois, fifth seed Olga Govortsova and qualifier Julie Ditty. In the championship match, she lost in straight sets to three-time Grand Slam champion Lindsay Davenport, who was playing in only her third event since giving birth.
After changing her citizenship from Ukraine to Spain in April 2008, she planned to play for Spain in the Fed Cup, but was not able to compete in the 2008 Summer Olympics due to lack of time to be included in Spain's application.