Lieutenant Erickson was an historian serving aboard the USS Enterprise under Captain James T. Kirk.
In 2269, with the assistance of the Guardian of Forever, Erickson joined Kirk and Spock in their observations of Federation history as well as firsthand accounts of Orion history. (TAS: "Yesteryear")
Erickson was voiced by James Doohan.
In the script of "Yesteryear", Erickson was described as "a small, intense man."