Your unknown robot is a Beanbot. It was an old Onell Design line that got shuffled into Glyos with some new parts as the Phaseon. They often got thrown into earlier Glyos orders, since Matt is always amazing about bonuses and the things did not take off on their own.
Your Solaris Gobon might not be missing its original head. That one is hidden inside the torso. If you take it apart entirely, it might be sitting in the cavity.
I don't see anything missing on your Glyan Enforcer. Every Glyan comes with an alternate matching head and it just varies for the heck of it whether the "official" default head is the helmet or the unmasked one.
The Gendrones and Buildmen, on the other hand, all have backpacks which included some extra pieces that could be used as adapters and two alternate heads. The Gendrone head is one of the alternates, with the other one being this triangular visored head. It looks as if the backpack is entirely missing on your dude, unfortunately.
Your Andromeda Pheyden comes with Solaris Excellis limbs. The reason for this seemingly random creation might be due to an old feature on the Onell Design store, the Junk Shop. This would be a random assortment of spare parts that had been amassed over several production runs, put together as complete figures and sold much cheaper than normal retail price. A lot of collectors got together on the old October Toys forum and would swap parts in an attempt to turn their random bits into complete standard figures and many were successful, but it took some work! This particular figure could be a more matching example of one of these, or maybe your friend wanted to mess around and mixed up the parts this way, but you're short the Solaris body with Andromeda limbs. Either way, it's a neat curiosity and would be desirable to the many fans of the Solaris glow in the dark color.
Ye of little faith, bronchuseven...