A person who performs menial tasks for someone else, often in a servile or obsequious manner. The executive's flunky was always running errands and fetching coffee.
A person who is excessively subservient or obsequious to someone in authority. He was seen as a flunky by his colleagues because he always agreed with the boss, no matter what.
A liveried servant, especially a footman, employed by someone of high social status. The flunky held the carriage door open while the guests climbed in.