That spike thing that punctures you in a way that none of your vital organs touched.
That helmet-thing where'd they pull on your neck and kinda dislocate it or something so you suffocate.
Getting pulled apart.
Burnt at the stake.
Crucified.
Basically I'm okay with anything from the Spanish Inquistion scene from History of the World Part 1. That's a funny movie...
A starflare bomb is strapped to his crotch. The bomb is VERY sensitive to shock and vibration. If he breathes, it explodes.
A supernova is strapped to his crotch. It just explodes while you're watching.
A laser/microwave slowly cuts off parts of his body until it's focused on his face.
He's shot with a stickyfoam grenade, which covers his face, so he suffocates.
He's shot with an ESG which electrocutes him to death.
Shot with an Acid Cloud Grenade with melts his skin off, then melts his organs.
Rail Gun/RPG to the chest.
Bombarded with Emp Grenades/Missiles until he dies from being hit by blunt objects.
Scorpion/spider climbs up him and slowly eats his face off.
Thor's Hammer rips his skin off or does whatever a Thor's Hammer would do to a person.
A ConVec/Repair Vec/Earthworker's manipulator arm rips his head off.
Robo Dozer makes him become one with the ground.
A Scout runs over him at such a high velocity he splatters all over the place.
A Cargo Truck dumps wreckage on him. The wreckage is full of sharp metal and glass objects.
He's locked in an Evac Transport which is driven into a volcano while he's in it.
A Robo Surveyor uses it's pick thing to slice open his chest.
A GeoCon/Robo-Miner builds on top of him and either drills through him or pushes him into the magma vent or fumarole.
Well, you have death by any Outpost 2 vehicle or weapon and a few other nasty fates. Pick one.