The Sith Triumvirate was formed after the remnants of Dark Revan's forces was scattered after The Jedi Civil War. Notable members of the Triumvirate includes Darth Nihilus, Darth Sion and Darth Traya

The Sivana Family are enemies of the Marvel Family.

They were a group of six Lesser Demons.

A team formed by Cable which was originally called the Wild Pack, but a conflict with Silver Sable forced Cable to change the name of his team to the Six Pack.

Myriad offshoots of humanity

The Skarabs are a race of fighters loyal to Zamora. After Zamora had died, they became loyal to her daughters, the Wicked Witches of the East and the West.

Group created by The Red Skull to preform missions for him. Lead at one time by Crossbones the crew was composed of other Red skull operatives. Ultimately they were defeated by Captain America.

A race of shapeshifters from planet Skifflefufflula. A small faction of them posing as Skrulls had a couple of run-ins with Young Avengers.

Men who follow the witchery way and are pure evil. They can assume any animal they like and even take over another person's body.

The Skalarian Raiders are various groups of all female space pirates from the planet Sklar bent on ravaging the space ways of the 31st century for technology.

Supernatural, demonic creatures sent to hunt down Conan.

An evil terrorist organization from Dimension Ecch.

The Norman's gang.

A team of individuals who gained their powers from Skrull DNA. They work together to exterminate all skrull influence hiding on the Earth.

"They called themselves Skrulls! But, by any name, they were a band of the most dangerous menaces Earth had ever faced! They are able to change their appearances at will!"

SKULL is an international criminal gang.

A one man, one dwarf, and one elf team of mercs, willing to take most any job that involves... kicking skulls!

A gang in New York City's Waterfront who rivals the Daggers.

Skull Squadron was the nickname of 1st Imperial Center Core Defense Squadron. It is an elite squad of starfighter pilots that flew TIE Predators.

Reptilian aliens who are highly intelligent and often sell their services to the highest bidder.

Led by Captain K-4

A breed of flying kangaroos on Paradise Island.

A group of intelligent triplets who make technology with the sole goal of taking down Green Arrow.

Immortals of planet Indigarr who were butchered by Gorr.

Skynet is sentient computer software created by the military. It becomes self aware and deems humanity a threat so it caused Judgement Day and send Terminators into the past to preemptively kill its foes in the future.

A team solely created to prove to the world that Superman couldn't save everyone. The team was later frozen to death by the Superman impostor.

The Skysharks were an international legion of ace pilots that fought the Axis Power in World War II. They settled in Neopolis after the war.

A winged Humanoid species.

The group Swordwalkers is a sci-fi space movie series that Dick Grayson and Damian Wayne are a fan of. Elements of Star Wars, TMNT, and Indiana Jones are used as inspiration.

World War Two team

The riders of the Boulder Mobile #1.

Also known as Revenants, the Slashers are the enemies of Cassie Hack and Vlad.

Enemies of Static, the Slate Gang are tech smugglers.

Reusable assassins.

Race of pirates from Earth-1289 reality, dedicated to capture and sell slaves.

Beings from across the universe caught by slavers and brought to Kral to fight in their gladiator style games.

The Slayers are a mystical line of women who are "called" to fight the forces of darkness.

Series of robots used by Red Skull.