Wiktionary
illeism
n. The practice of referring to oneself in the third person.
Wikipedia
Illeism
Illeism (from Latin ille meaning "he, that") is the act of referring to oneself in the third person instead of first person.
Illeism is sometimes used in literature as a stylistic device. In real life usage, illeism can reflect a number of different stylistic intentions or involuntary circumstances.