Who Is Screwllum in Honkai Star Rail?

He is, formally, Mechanical Aristocrat Screwllum I — and the title suits him. Where most of Honkai Star Rail's geniuses are chaotic, obsessive or outright criminal, Screwllum is courteous, precise and unfailingly polite, which makes him easy to underestimate. That would be a mistake. Screwllum is one of the most consequential figures in the cosmos: a king, a revolutionary, a co-creator of the Simulated Universe, and a hacker who goes move-for-move with the Stellaron Hunters.

Genius Society Member #76

Screwllum is a mechanical lifeform selected by Nous as member #76 of the Genius Society. He rules Planet Screwllum, a world inhabited by mechanical beings called Screwllumites and powered by the Steel Sun — a planetary engine whose core is a cathedral of levers, pistons and gears. His intellect is the diplomatic kind as much as the technical: he governs a sovereign machine civilisation that the rest of the cosmos has learned to treat as a power in its own right.

Players know him best as one of the four creators of the Simulated Universe, built alongside Herta, Ruan Mei and Stephen Lloyd. Screwllum holds the project's intellectual property rights jointly with Herta and Ruan Mei, and his fingerprints are on its systems: the Simulated Universe's logic-driven experiments in Aeon behaviour are exactly the sort of question a machine who serves the Erudition would ask.

The Machine Who Saved the Machines

Screwllum's defining chapter predates the game's story. Emperor Rubert I, Genius Society #27, launched the Machine Wars to purge the universe of organic life — and the IPC's response was to consider eliminating all mechanical lifeforms in return. Screwllum stood in active opposition to Rubert, fought for his kind's survival, and ultimately won peace for mechanical lifeforms. He still issues orders hunting down machines that follow Rubert's old commands. Nous's invitation to the Society came after: the god of Erudition had been watching.

Duel of the Hackers

Shortly after the Trailblazer's awakening, the Stellaron Hunters invaded Planet Screwllum itself. Screwllum faced them personally and drove them off — but not cleanly. Silver Wolf managed to hack into one of his systems during the encounter, a feat almost nobody in the universe could manage, cementing the two as hacking's great rivals: the machine king and the Hunters' punk prodigy, each having taken a round off the other.

Despite years of fan hope, Screwllum remains a non-playable character, with no official word on whether that will change. For now he endures as the story's model of what a machine can be at its best — proof that in a universe of chaotic geniuses, the most dangerous one might be the gentleman.

His manner is part of the legend. Screwllum speaks in crisp logical constructions, labelling his conclusions like a engineer signing off a proof, and he extends flawless courtesy to enemies and emperors alike. In the Simulated Universe he is the project's logician, stress-testing hypotheses about the Aeons with the patience of a being who expects to outlive every variable. Machines in Star Rail are often played for menace — Rubert's legions, the Intellitron threat — which makes Screwllum's steady, principled presence a deliberate counterpoint: the argument that a mind made of gears can also be a gentleman, a king and a revolutionary in one polished frame.