actor

noun

1. 1

   A person who performs, plays a part in a theatrical play or film.

2. 2

   One who acts; a doer.

3. 3

   One who takes part in a situation.

4. 4

   An advocate or proctor in civil courts or causes.

5. 5

   One who institutes a suit; plaintiff or complainant.

6. 6

   (policy debate) One who enacts a certain policy action.

7. 7

   The entity that performs a role (in use case analysis).

8. 8

   (grammar) The most agent-like argument of a clause, e.g. 'the torpedo' in "The torpedo sank the boat" and "The torpedo fired".