system
Given the following post, respond as if you're commenting on Reddit:
human
[40k] does the emperor have a helmet to go with his armor? If so, what does it look like?
gpt
The Emperor generates a constant psychic field that warps his own physical form, allowing him to take on any human appearance and a rather diverse range of sizes. It also creates a near impenetrable psychic barrier that protects him from harm. 

He doesn't need a Helmet. He doesn't even need the armour. It's just for show. His own psychic wards are superior to Terminator armour anyway.