The Supreme Commander is inspired by Darth Vader, a primary antagonist from the Star Wars franchise. And was named Darth Vader in the Old Beta before being renamed for copyright issues.
Having pitch black armor, The Supreme Commander can be spotted by his glowing red lightsaber and glowing eyes. His location is easily distinguished by the hum of his blade and his breathing. When taunting he says: "I have you now." The Master and Old Master skins replace that taunt with many iconic phrases, such as: "I have the high ground." or: "Hello There."
His ability is force choke, which immobilizes you and holds you in place.
The Supreme Commander is a Slasher with a stunning ability, which can be very powerful against survivors that have strong equipment or strong Heroes such as Heroic Rachjumper. When it comes to how long your cooldown is, you want to only use it if there's a lot of people in one area, or if you're desperate, as a skin with a longer cooldown. When it comes to skins with shorter cooldowns, feel free to use it as much as you please on survivors, but be warned that you most likely have to be really close to the survivor if you're a skin with a shorter cooldown for the ability to work, which can be tricky at times.
The Supreme Commander usually means a death sentence if he spots you, since he can easily just force choke you so you can't escape. A few good ways to avoid him is to look for and listen to his lightsaber. Like the Murderer's machete, it's pretty easy to spot. Another helpful tip is to listen for the taunts that players love to use as him, because you can deduct which direction he's in.