Hugo Dellien Velasco (Spanish pronunciation: [ˈuɣo ðeˈljen];[a][1][2][3] born 16 June 1993) is a Bolivian professional tennis player.

At the 2019 Rio Open, Dellien defeated Carlos Berlocq in qualifying competition, Guido Andreozzi in the first round, and Roberto Carballés Baena in the second to reach the quarterfinals.

Hugo became the first Bolivian player with an ATP win since Mario Martínez at the French Open in 1984, trailing 3–1 in both sets before performing a comeback against Andreozzi to secure a historic achievement for both him and his country.

At the 2023 Córdoba Open, Argentina he reached again the quarterfinals as a qualifier defeating two Argentines, fifth seed Pedro Cachin[7] and Guido Pella.

At the 2023 Rio Open, also using a protected ranking, he reached the quarterfinals for a second time in four years at this tournament with a win over ninth seed Alex Molčan in the round of 16.

[11] Their father, Hugo Eduardo Dellien,[12] represented Beni Department as a substitute member of the Chamber of Deputies for the Social Democratic Power alliance from 2006 to 2010.

Dellien is married to retired tennis player Liz Camila Giangreco Campiz; the couple share a daughter.