Higgs Monaghan, also known as the "Man in the Golden Mask", is the main antagonist of Death Stranding. He is the leader of the militant separatist group known as the Homo Demens. Higgs was raised by his uncle early in his life after both of his parents died. His uncle refused to let Higgs leave their shelter and would beat him whenever Higgs asked about the outside world.

Higgs would eventually kill his uncle in self defense with a knife and witnessed the body becoming a BT after having to dispose of his corpse, gaining his DOOMS in the process. Higgs founded the militant separatist group known as the Homo Demens, who oppose the United Cities of America and seek to maintain the independence of Edge Knot City.

While confronting Sam in Port Knot City, Higgs claims to understand the truth of the Death Stranding. He uses his powers to summon the same BT Sam sees whenever he is taken. Higgs disappears, leaving Sam to kill the BT or total Port Knot with a voidout. After leaving Mama's Lab, Higgs appears before Sam and manifests a large, four-legged BT, issuing the deliveryman a challenge: avoid being eaten. At another point, Higgs goes to the beach and steals Amelie's quipu.

Sam sees this in a vision where Higgs stabs her in the neck. Higgs and Sam have their final confrontation on the beach. After Sam defeats Higgs, Fragile gives Higgs the choice of suicide or being stranded on the beach. Higgs later wrote about his defeat in his journal, before writing about his childhood. Highly meticulous and malicious, Higgs has no qualms nor moral boundaries when orchestrating ruthless acts of slaughter and gleefully participates out of fun and personal enjoyment.

Holding an aura of unshakable confidence, charisma, and sarcasm, he rarely loses his cool and consistently maintains a composed and collected personality. No holds-barred when engineering voidouts killing thousands for that reason as well as to install fear in the cities guided and united under the UCA Alliance, and to facilitate the extinction of humanity.

Higgs has a layer of dark humor when confronting Sam and Fragile as well as overall. Musing about death and destruction of the first POTUS, and noting that Amelie wasn't cut out for a similar role. Having no restraint over his men and sees them as infallible and loyal. Highly egotistical and arrogant. Higgs views himself as greater than humanity, yet also has accepted the inevitability of the sixth extinction event. In his dealings with other humans, especially Sam Bridges, he uses his chiralium control as demonstrations of his superior nature.

Despite his violent behavior, Higgs demonstrates a very high intellect and understanding of various concepts prior to Sam and Fragile. Higgs displays his worst traits through an affable exterior that hides his more evil intentions. He once believed in the preservation of the UCA and actively supported their cause. Due to him meeting Amelie, he finds out the truth about everything and becomes a hyper-fatalist hellbent on creating about a mass extinction of humanity, the sixth such event.

He implores Sam to cave in to the reality of his apparent inevitable destruction. His philosophy is heavily influenced by his realization of extinction entities and their purpose. As noted above, he accepts this fate without pause, and even manipulates Sam into helping the acceleration of the 6th Extinction Event. Higgs carries a portable tank with a fetus-shaped figure inside.

Rather than emitting an orange-yellow glow when activated, as the bridge baby's pod does, his portable pod emits a red one. The bottom casing of Higgs' pod is also green, rather than orange like the bridge baby's. Inside of the pod is an old, corroded baby doll that connects him to Amelie. Underneath his golden mask, Higgs wears another black mask.

Both he and Sam began as porters. Higgs' successes and admiration from the communities inflated his ego but made him susceptible to a fall to madness after he met Amelie. Sam managed to remain humble and remember the purpose of helping connect others and chose to carry on living even after learning of Amelie's true nature.

He mails Sam under the pseudonym Peter Englert. Each mail is about delivering a pizza, claiming to be Sam's greatest fan, and pleasing a (non-existent) relative.

Source: https://deathstranding.fandom.com/wiki/Higgs_Monaghan