5. Allan Pinkerton
Public DomainThe seeds for this man's appearance have actually already been sewn. In the final episode, the men we see confront Ethan Chandler in the pub introduce themselves as Pinkerton agents, before Ethan brutally slays them. The Pinkerton Detective Agency was a real life outfit based in the U.S. around that time period and they were renowned as being the world's first real private investigation firm. The fact that two agents would board a ship and pursue their prey overseas means Chandler must be a very important collar for them. Perhaps important enough to have the head of the agency, Allan Pinkerton himself, investigate when the men he sent turn up dead. We like Mad Men and Sherlock Holmes star Jared Harris in this role, Pinkerton as a determined bounty hunter trying to catch Chandler who is technically in the wrong.