Adelperga (born c. 740 – died after 787) was an Lombard noblewoman, daughter of Desiderius, King of the Lombards, and his wife Ansa. She was the third of four daughters of king Desiderius. Her elder sister Desiderata was a wife of Charlemagne.
Adelperga was tutored by Paul the Deacon. In c. 757, she was married to Arechis II, Duke of Benevento. She remained in contact with Paulus, who at her request wrote his continuation of Eutropius in c. 775. Paul also dedicated to Adelperga his Versus de Annis, an acrostic spelling Adelperga pia.
Adelperga and Arechis had five children,
Grimoald (before 773 – April 806)
Gisulf (d. before 806)
Theoderada (d. after 787)
Adelchisa (b. after 773, d. after 817), abbess of San Salvatore d'Alife
After the fall of the Kingdom of the Lombards to Charlemagne, Adelperga's parents and sister were exiled to Francia, where they were imprisoned in religious houses. Adelperga and her other sister Liutperga then embarked upon a struggle to regain their patrimony and take revenge upon Charlemagne. Liutperga ultimately brought ruin upon herself and her family by encouraging her husband Tassilo to rebel against Charlemagne, his cousin: Charlemagne discovered Tassilo's plots and confiscated all his goods. Tassilo, Liutperga and their children were then banished to monasteries.
Adelperga was more successful; her husband resisted Charlemagne for some time, until in 787 he agreed to make peace with Charlemagne; at the encouragement of his wife and the Byzantines, he refused the peace treaty, which would have entailed surrendering part of his duchy to the Papacy. Adelperga and Arechis sponsored the church of Santa Sofia in Benevento.
When Arechis died on 26 August 787, Adelperga acted as a regent for a few months because Charlemagne hesitated to release Adeleperga's son Grimoald, whom he kept as a hostage.
Grimoald was released and acceded as duke in February 787. After this, there are no further mentions of Adelperga. Grimoald swore fealty to Charlemagne and defeated a Byzantine invasion commanded by Adelchis.