Also, I have a box of parts. If I display the heads, will that lead me to what these are?
Thanks for any help. My grandson loves to put LEGO parts together so I want to take these apart and have instructions for him.
The two Bionicles on the right are for sure a mix of different parts from different sets, and, without seeing much close-up details, it will be very difficult to tell you which original sets the parts came from. The white piece on the foreground is part of an Exo Force set from 2006 called 7700 Stealth Hunter (https://www.bricklink.com/v2/catalog/catalogitem.page?S=7700-1).
The set on the left might largely consist of pieces from one specific Bionicle, but I have not been able to identify him yet. However, the whole idea behind the Constraction sets like Bionicle and Exo Force is that you can combine them and make your own creations, which seems like what you have here. Your grandson should have a blast playing with them, no matter if they belong to a set or not. Have fun!