Syncellus or synkellos () is an ecclesiastical office in the Eastern Catholic or Orthodox Churches.

As part of a name, it can also refer to several people who bore this title:

Euthymius I Syncellus, Byzantine ecclesiastic, Patriarch of Constantinople in 907–912 George Syncellus, 9th-century Byzantine chronicler and ecclesiastic Michael Syncellus, 9th-century Byzantine saint

See also Protosyncellus