Gabriel, a Hebrew name meaning "God is my strength," may refer in Harry Turtledove works to:

Characters known only as Gabriel:

Archangel Gabriel, theological figure occasionally referenced in Turtledove works, most importantly in "Departures", prequel to Agent of Byzantium.

Characters known only as Gabe:

Gabe (Iron Heart), fictional US Army medic, minor character in The Man With the Iron Heart.

Characters whose first name is Gabriel:

Gabriel Medwick, fictional Confederate soldier in Settling Accounts.
Gabriel Pruitt, fictional journalist, minor character in The Two Georges.
Gabriel Sanchez, fictional policeman in Supervolcano.
Gabriel Semmes, fictional Confederate politician in Southern Victory.

Characters nicknamed Gabby:

Gabby Priest, fictional US Army soldier, minor character in Settling Accounts: Return Engagement.

Characters whose first name is Gavrilo, a Slavic version of Gabriel:

Gavrilo Princip, historical terrorist referenced in Hitler's War.