Bob Probert, may his fists rest in peace. The consummate professional, he never looked back from a fight; once the last punch was thrown he just skated off and did his time. You definitely got the impression that the fighting was never personal, and this is important to consider if you're entering the assassin trade. It's a business; you take the job, you do the work, you move on. A detached sense of morality is crucial.
Two of the heavy weights:
If you are interested in the Thuggee cult, check out Pierce Brosnan in The Deceivers, or, if you're one o' them literary types, read the book of the same name--written by John Masters--upon which the film was based. I actually watched this movie a few years ago whilst on a Brosnan bender that included Matador--a great movie on the topic of assassins.