1) Captor 2) Capturer 3) Giver of a certain party 
• (n.) One who surprises.
Sur·pris'er noun One who surprises. 
[n] - a captor who uses surprise to capture the victim
surpriser 1. A captor who uses surprise to capture a victim. 2. Someone who attacks unexpectedly; also, anyone who captures by an unexpected attack. 3. Anyone who takes someone, or people, unexpectedly.
noun a captor who uses surprise to capture the victim