Acacius of Caesarea was a Christian bishop and theologian of the 4th century CE. He served as the Bishop of Caesarea in Palestine from around 340 CE until his death in 366 CE, succeeding his mentor, the historian Eusebius. Acacius became a leading figure in the major theological debates of his time. He was associated with the Homoian party, which sought a middle position on the nature of Christ, rejecting both the Nicene view and the more radical Arian position.

None of Acacius's own writings survive intact. According to historical sources, he authored a treatise against another theologian, Marcellus of Ancyra, a biography of Eusebius, and a collection of accounts of martyrdoms. He was also known for his scholarly work, including a critical edition of the Gospels, but no details of these projects remain.

Modern scholars see Acacius as a central and polarizing figure in the complex religious politics of the 4th-century church. His significance lies in his role as a key intellectual and political force for the Homoian creed, which enjoyed temporary official support. Although the Homoian theology he championed was ultimately rejected by later church councils, Acacius represents an important strand of theological thought during a formative period in Christian doctrine.