A person who is killed because of their religious or other beliefs. Saint Stephen is considered the first Christian martyr.
A person who displays or exaggerates their discomfort or distress in order to obtain sympathy or admiration. He was being a martyr about having to work late, hoping for some praise.
A person who suffers severely or constantly from something (such as an illness), especially used in the expression “a martyr to …”. She's a martyr to arthritis and can barely walk some days.