Duquesne University of the Holy Spirit ( dew-KAYN; also known as Duquesne University or Duquesne) is a private Catholic research university in Pittsburgh, Pennsylvania, United States. Founded by members of the Congregation of the Holy Spirit, Duquesne first opened as the Pittsburgh Catholic College of the Holy Ghost in October 1878 with an enrollment of 40 students and a faculty of six. In 1911, the college became the first Catholic university-level institution in Pennsylvania. It is named for an 18th-century governor of New France, Michel-Ange Duquesne de Menneville.

Duquesne has since expanded to over 9,300 graduate and undergraduate students within a self-contained 49-acre (19.8 ha) hilltop campus in Pittsburgh's Bluff neighborhood. The school maintains an associate campus in Rome and encompasses ten schools of study. The university hosts international students from more than 80 countries, although most students—about 80%—are from Pennsylvania or the surrounding region. Duquesne is classified among "R2: Doctoral Universities – High research activity". There are more than 93,000 living alumni of the university ranging from two cardinals and the former bishop of Pittsburgh to a former director of the Central Intelligence Agency.

The Duquesne Dukes compete in NCAA Division I. Duquesne men's basketball appeared twice in national championship games in the 1950s and won the NIT championship in 1955.