John Gordon Mein (September 10, 1913 – August 28, 1968) was the first United States ambassador to be assassinated while serving in office.

[2] Mein served as the United States Ambassador to Guatemala during the Guatemalan Civil War.

It was during his tenure that alleged U.S.-backed state terrorism which started after the 1954 Guatemalan coup d'état greatly accelerated with forced disappearances and massacres.

U.S. officials believed that FAR intended to kidnap him in order to negotiate an exchange, but instead they shot him when he attempted to escape.

[6] Mein was also memorialized in the Department's Diplomatic Lobby along with other Foreign Service personnel that have died in the line of duty.