Defector (noun)

1. A person who renounces allegiance to their country or cause and defects to another.
2. A person who abandons their party, organization, or cause to join an opposing one.

Origin:

Mid-17th century, from latin defect- ("fault, failure") + -or.

Examples:

1. He was a defector from the Communist party who sought asylum in the United States.
2. The defector provided valuable information about the enemy's plans.
3. The company lost several key employees who defected to a competitor.
4. The government tried to prevent the defector from leaving the country.
5. The defector's decision to leave the organization caused a major crisis.