Agapetus (Ancient Greek: Ἀγαπητός, beloved) may refer to:
- Agapetus (caddisfly), a genus of caddisflies
- Agapetus (deacon) (fl. 500–527), a deacon of the church of Hagia Sophia in Constantinople
- Agapetus (physician), ancient Greek doctor
- Pope Agapetus I (died 536)
- Pope Agapetus II (died 955)
- Agapetus of the Kiev Caves (died 1095), saint of the Eastern Orthodox Church
- John IX Agapetus (died 1134), Patriarch of Constantinople
- Agapetus, pen name of Yrjö Soini (1896–1975), Finnish journalist, novelist and playwright