invoker
(noun)
noun
1. One who calls upon (a person, especially a god) for help, assistance or guidance.
- An invoker of God's mercy
2. One who appeals for validation to a (notably cited) authority.
3. One who conjures up spirits with incantations.
4. Someone who induces as an inevitable consequence.
5. One who solicits, petitions for, appeals to a favorable attitude.
6. (computing) That which causes a program or subroutine to execute.