Ethan Mathews (fake)
- Full Name: Unknown
- Also known as: Ethan Mathews
- Species: Klingon
- Gender: Male
- Surgically altered to more resemble a Human for purposes of infiltration (TOS Novel: Errand of Vengeance: The Edge of the Sword)
- By 2266: Imperial Intelligence, Klingon Empire (TOS Novel: Errand of Vengeance: The Edge of the Sword)
- Recruited for betleH 'etlh (TOS Novel: Errand of Vengeance: The Edge of the Sword)
- January 2266: Embedded as security officer, Starfleet; USS Enterprise (TOS Novel: Errand of Vengeance: The Edge of the Sword)