1. An authentication system comprising: an imaging device configured to capture a thermal image of a user and a non-thermal image of the user; and a processor in communication with the imaging device, wherein the processor is configured to: derive, based on the captured thermal image of the user, a thermal profile indicating temperature variations within an area of the captured thermal image corresponding to at least a portion of the user; recognize the user based on the captured thermal image and the captured non-thermal image, wherein the recognize the user comprises comparing the derived thermal profile against a stored thermal profile associated with the user; and in response to determining that the user is recognized as an authorized user, authenticate the user by providing the user access to a secure system and/or alerting security personnel that the user is recognized as an authorized user.