Lord General Freddie Stalin "Mercury" Melchett-Castor is the Imperial commander of the Cadian forces sent to fix all the weird shit going on in sub-sector Aurelia.
After hearing many reports of Aurelia's frequent problems and the Imperial Guardsmen's inability to get shit done,
Castor Adrastia decided that enough was enough and decided to take matters into her own hands and started a party. Castor was invited because she doesn't like tactics and he does. He accompanied Inquisitor Adrastia and Commissar LORD Bernn. He later met up with Sergeant Merrick after he was incapacitated during a Tyranid ambush (Which he joked that Merrick may still be "salvageable"). After killing the Tyranid Hive Tyrant and adding its head to his ridiculously enormous collection of trophies, he was informed that the Ordo Malleus would perform Exterminatus on the entire sub-sector (Ordered by the corrupted Chapter Master Azariah Kyras). Castor assisted Adrastia in her investigation. After finding evidence of Kyras' corruption, they proceeded to travel to the planet Typhon to confront Kyras for his HERESY. After killing the Eldar stationed there, they discovered, too late, from Kyras, that the Eldar were actually preventing the Exterminatus fleet from entering the sub-sector. So after escaping the planet, teleporting to a space hulk and escaping from said space hulk, Castor finally confronted the now transformed Mega-Uber Daemon Prince Kyras in the dead world of Cyrene. After a SHORT battle (Seriously, the massive Guard army Castor brings makes it piss easy), Kyras is defeated.
Castor is arrogant, cocksure, sarcastic, laid back and a huge glory-hog. He has the voice of a upper-class Englishman, has the looks of an older Freddie Mercury and sometimes, the mannerisms of a colonial big game hunter. (So he also ACTS like Freddie Mercury... kidding) He has absolutely no qualms of sending countless guardsmen to their deaths just so that he could make another gargantuan effort to move his trophy cabinet six inches closer to the enemy base. He does this for the lulz. He has a fetish for collecting dangerous creatures and xenos heads (particularly Tyranids) for his impossibly fuckehuge collection. Despite being seen as a proud, boastful and quite clueless general, he is very intelligent and cunning. He even knew that Kyras was on Cyrene, due to the fact that Cyrene had already undergone Exterminatus and was therefore passed over by the currently operating Exterminatus fleet( you don't have to be a genius for understanding that anyway, considering that a certain ork kaptin find that out too.)
Having lost his left arm, he replaced it with a bionic replacement that allows him to wield weapons like sniper rifles, flamers, meltas, bolter guns, or plasma guns with only one hand. He also wields a sabre in his relatively intact right hand. He can kill space marines and tyranid warriors in melee, which is awesome, and with the melta he becomes a rape machine with his retinue. Seriously, spam the fuck out of meltas in the IG campaign and everything will die ridiculously fast.
Unlike many other Imperial Lord Generals, Castor is badass enough to get right into the fighting and is a very skilled fighter and a balls out badass, more than making up for the fact that besides his mechanical arm, he's just a regular human in carapace armour. This combination of traits has elevated Castor to the same lofty heights of Cain, Gaunt, and Sturnn in terms of Imperial Guard characters. Plus god damn that moustache.
According to the 'The Battle of Tyrok Fields' by Justin D. Hill, Ursakar Creed had an adjutant by the name of Castor. We may reasonably presume that, with so many senior officers killed at Tyrok Fields, Castor received a promotion for his efforts, grew an awesome mustache, and was packed off to Aurelia.
(After saving Sergeant Merrick from a Tyranid ambush)
Merrick: "Thank you, General. I thought this might finally be it."
Castor: "Your lack of cowardice is refreshing, Sergeant Major, but your weakness is typical of this sector. I'll toughen you up, or use you up. Perhaps both as the Imperium requires."
(After encountering the Tyranid Hive Lord)
Castor: "A magnificent specimen, don't you agree Merrick?"
Adrastia: "You admire the horror, General?"
Castor: "Indeed. Its head will go nicely in my trophy collection. Aim low."
(After defeating the Hive Lord)
Castor: "This beast is strong but strength is no match for intelligence and resolve."
Merrick: "Or large caliber explosive rounds, for that matter."
Castor: "Now you're getting into the spirit, Sergeant Major."
(After the group narrowly escapes from the Exterminatus of the planet Typhon. It's important to keep in mind Merrick begins the following conversation by striking Castor with the butt of his rifle and spends the rest of it with Commissar LORD Bernn's pistol pointed at his head as well as a grumpy Inquisitor who hates him standing three feet away. Balls of steel indeed)
Merrick: "You bloody arrogant fool!"
Castor: "Merrick! Stand down!"
Merrick: You killed them all, Castor! All of them, gone, because of your incompetence!"
Castor: "You think I'm incompetent? Sergeant Major, the destruction of Typhon was inevitable. Between the Eldar, Orks and Tyranids there was no saving that world. At worst I helped speed its demise. And at a time when there were relatively few men on the planet."
Merrick: "Few? Few?! There were THOUSANDS of guardsmen on Typhon! Good men, serving the Emperor, and you let them all die!"
Castor: "Merrick, a guardsman's LIFE is to die. My job has always been to send them to places where they CAN die. I'm not afraid to spend them, but I never waste men. Because of their sacrifice the Inquisitor has the proof she needs. You do have the proof you need, don't you, Inquisitor?"
Adrastia: "I FELT Kyras. What was inside him. He is not...alone."
Castor: "Then I suggest we find him so we can end this once and for all."
Adrastia: "Where? I was inside his mind and still could not tell you that."
Castor: "ONE planet will be spared, because it has already been cleansed. Decades ago."
Castor: "Where better to hide than a dead world? Kyras will be waiting there, I promise you, feeding on the death of the other worlds."
Merrick: "And...and you knew this all along?"
Castor: "Much of it. He's not as clever as he thinks he is. I put the rest together on Typhon. Now, Sergeant Major, you can proceed with your attempt to kill me. But as I mentioned, I don't waste men if I can avoid it, and killing you for insubordination would be very...wasteful. Are you with me?"
(After the group's defeat of the ascended Azariah Kyras and Inquisitor Adrastia's departure)
Merrick: "Can't say I'm sorry to see her go, sir."
Castor: "I share your sentiments, Sergeant Major. Though it's a poor excuse for an Inquisitor that doesn't make people uncomfortable. You are to be commended on your performance these past few days. Which is why I am putting you in for a medal, and not having you shot for insubordination."
Merrick: "Thank you sir. And you've turned out to be a good commander. *under his breath* Which is why I didn't have you shot for incompetence."
Castor: "What was that?"
Merrick: "I said I was shocked by your competence, sir."
Castor: "Baaaah! That's what I thought you said. Carry on, Sergeant Major...carry on."
- He's voiced by Richard Doyle. Quite known as the voice of Ulyoath and Pious Augustus from Eternal Darkness, The Fury and Big Boss (This makes his ability to deploy a squad from a flying box meta AF) from Metal Gear Solid, Enoch from Ben 10 and Moebius from The Legacy of Kain.
- He may be descended from Blackadder's General Melchett. Which may explain his habit of sending millions of guardsmen to their deaths.
- There is no mention of Castor in the Cain archives, even though the two almost certainly served together. This may have something to do with an incident involving a psyber pigeon message courier, or the untimely death of Castor's fiancée.
- He has a mustache that would make all the Imperial commanders jealous which, if a space marine had, would make even him collapse to ground unless the marine is wearing terminator armor.
- He's Creed's second cousin; despite the fact that said cousin rarely mentions him and vice-versa. (Crap is this true or a lame excuse for a joke?...)
- At least during the Aurelia Campaign, he was authorized by said cousin to use a slightly less powerful -but still incredibly useful- version of Tactical Genius. Sadly, he can't turn rocks into Baneblades, (at least, not yet) but woe to the unfortunate foe who sees a Valkyrie Transport dropping a Metal Box in the middle of the battlefield (Even aboard an uncharted space hulk accessed through a collapsing teleportarium). Said box may turn into either infantry or a Leman Russ. There's a reason why it's been nicknamed the Box of Rape.
- Lost his left arm after having it eaten by a Hierophant Bio-Titan during the battle of Philippinia VII.
- Aforementioned Hierophant Bio-Titan's head is now on his Trophy wall.
- Has an Impossibly HUEG Trophy Room.
- Said Trophy Room has the head of every single Tyranid species/sub-species ever encountered by the Imperium... EVER.
- He's also manly enough to ask noise marines if they can hear him say 'shoot them now'.
- What's even more awesome than the things before this, is that he references Monty Python's Spanish Inquisition. Seriously. In the mission where you are ordered to destroy an Eldar Seer Council, he says this: 'We have lost the element of surprise, and they do not fear us. Perhaps they will appreciate our devotion to the Emperor and our ruthless efficiency.' The original Monty Python sketch told us the Spanish Inquisition relied on five elements: fear, surprise, ruthless efficiency, an almost fanatical devotion to the Pope and nice red uniforms. Castor must have been raised properly that he references Monty Python.
- Every hair in Castor's mustache has killed more 'nids alone than entire space marine chapters put together.
- He KILLS Space Marines in melee. MELEE!!!!! Not every commander in the IG can do that