illeism
The practice of (excessively) referring to oneself in the third person.
countable, uncountable
[…] "[I]lleism with a difference" occurs when a character, speaking in the first person, refers to himself by name (not simply by a pronoun, which is illeism proper). [William] Sh[akespeare] makes significant use of the device in only four "middle plays." […] This sort of illeism enriches the dramatic context […]
Where it comes from
From Latin ille (“that man; he”) + -ism, modelled on egoism.
Adapted from the Wiktionary entry illeism (CC BY-SA 4.0).