Vladimir Mikhaylovich Petrov was a member of the Soviet Union's clandestine services who became famous in 1954 for his defection to Australia.

In politics, a defector is a person who gives up allegiance to one state in exchange for allegiance to another, changing sides in a way which is considered illegitimate by the first state. More broadly, defection involves abandoning a person, cause, or doctrine to which one is bound by some tie, as of allegiance or duty.