A variety of media players will support hard drive based files for playback. That also includes flash drives. My main player is a Patriot Box Office now discontinued. That player allowed for an installed 2.5" hard drive but I usually run it off a USB 3.0 flash drive or WD 500G portable drive. ASUS Oplay but that one is also discontinued.
The spare room player is this one:
Works well for a secondary stand alone system. Some of the players will not have enough juice through the USB 2.0 to spin-up the USB 3.0 portable drives. This is why I use 500G USB 3.0 on these players, they recognize pretty quickly.
WD TV series is also common among these types.