n. - A person who has in his/her possession incriminating pics or video of another. This person now has the power to kill your future (jobs, promotions, significant others).
1. Billy Bob: Dang Jethro, Earl is showin' everybody that picture of you with that sheep at the last company picnic - aint no way yur gitten that promotion to janitor now!
Jethro: Yeah, Earl sure is a future killer.
2. Monique: Hey Kathleen, did you know somebody took a picture of you with your dog and is posting it all over school?
Kathleen: I know, I have to find out who the future killer is before that pic hits the internet!