Count Ernst Adalbert von Harrach (4 November 1598 – 25 October 1667) was an Austrian Catholic Cardinal who was appointed Archbishop of Prague and Prince-Bishop of Trento. His name in Czech is Arnošt Vojtěch hrabě z Harrachu.
Adalbert von Harrach was born 4 November 1598 in Vienna, Austria, the son of Count Karl von Harrach and Maria Elisabeth von Schrattenbach. He was educated by Nikolaus Walther and was later, thanks to his family's connection to Italian aristocratic families including the Borghese and Barberini, admitted to the Collegio Teutonico in 1616. In 1621 he was ordained a priest at age 22 and became privy chamberlain to Pope Gregory XV.
In 1622, at only 24 years of age, Adalbert von Harrach was elected Archbishop of Prague with dispensation for not having yet reached the canonical age. He was consecrated and ordained in 1623 in the Sistine chapel by Cardinal Marcantonio Gozzadini.
In 1626 he was elevated to Cardinal by Pope Urban VIII and in 1632 he was appointed Cardinal-Priest of Santa Maria degli Angeli e dei Martiri where he served for 12 years. He was appointed Cardinal-Priest of Santa Prassede in 1644 and participated in the Papal conclave of 1644, which elected Pope Innocent X.