The term "right-hand person" indicates someone who is a valuable assistant or a trusted confidante, but when it comes to antonyms, the options could vary. A 'left-hand person' could be used to indicate someone who is the opposite of a 'right-hand person.' However, this term is rather uncommon in usage. 'Enemy' or 'rival' could be potential antonyms for right-hand person which means someone who is not trusted or relied upon. Some other terms that could be considered antonyms of a right-hand person include 'detached,' 'ignored,' 'role-less,' and 'excluded.' Ultimately the antonym of a right-hand person could be someone who is not perceived as valued, reliable or trustworthy.