10. Don Ramsey
We kick off the list with a season 11 character. Don Ramsey (David Lee) is the Chicago city treasurer, and he was introduced to the audience when he was caught cheating on his wife during a fire. A bad first impression to say the least, but things got worse when he demanded that his secret be kept under wraps.
Ramsey went as far as to threaten to ruin the career of Darren Ritter (Daniel Kyri) if he said anything about his extramarital activities. “If anyone finds out I was the unidentified man, I will ruin you, your Lieutenant, and this whole firehouse," he asserted. "Do you understand?”
A threat rather than a deadly action, but still high in the hated category.