- "Everything here will cease to exist. A black hole has no need for such things as emotions. You should... be happy. You will live forever within the darkness. You will be mine."
- ―Sirius, Mega Man Star Force 3
Sirius (シリウス Shiriusu?) is a character of the Mega Man Star Force series, and appears as the secret boss of Mega Man Star Force 3. He is the controller of a black hole, and uses it to attack other planets and stars, sucking them up and adding them to his "collection". He comes off as rather condescending and childish due to his lack of concern as to what happens to said planets and how he views all others as beneath him. When he attacks Planet AM and Planet FM, the Satellite Admins and Cepheus turn to Mega Man for aid. At some point in time he also acquires a Mu Metal that belongs to Rogue.
Sirius also happens to have rebuilt copies of the other EM Beings throughout the game, and the player must defeat these copies in order to fully progress through to the Black Hole Server. The rebuilt forms are labeled with "R" at the end of their names, save for Apollo Flame. After defeating these forms scattered throughout the EM World, the satellites that pinpointed their location now generate image data for the player to battle. When Sirius is finally defeated, he gives Mega Man the Mu Metal (in order to force he and Rogue to "fight eternally") and transfers his powers to Meteor G out of spite, causing Crimson Dragon to eventually upgrade itself into Crimson Dragon SP. He is the Greater Scope Villain of MMSF3, as while he doesn't directly affect the plot until the confrontation with him, he's far more dangerous a threat than any antagonist in the series by leaps and bounds. Sirius can be thought of as Star Force's equivalent of MegaMan Juno from Mega Man Legends, as his visual design and personality are both very similar, as is his ultimate role.
- Super Armour: Sirius cannot flinch.
- Status Guard: Sirius is immune to status ailments except for countering-induced paralysis.
- Glass Barrier: The middle row of the battlefield is protected with regenerating, 1 HP glass barriers, which can be avoided through the use of two Area Eaters or one Double Eater.
- Format Laser: Sirius fires a narrow yellow laser at the player from his wings, canceling any special panels, Barriers, and Auras that it comes into contact with.
- Wing Assault: Sirius launches his wings, which then fly down different columns to aim at MegaMan. They can be destroyed or dodged, but cannot be blocked.
- Wing Formation: Sirius launches his wings, which then shuffle about the field, firing lasers in random formations, covering different portions of the player's row. Each laser follows an element - Fire/Aqua/Elec/Wood - and it is possible for one row to be attacked by more than 1 laser at once.
- Satellite Blazer: Sirius floats up and fires a laser that will sweep the entire field, destroying every normal or cracked panel except those on his current row. This attack also hits the middle column twice, and Air Shoes are required to properly dodge this attack. He can not be harmed during this attack.
MegaMan: We... won.
Omega-Xis: That was a close one.
MegaMan: I don't want to compliment him, but he sure was strong.
Omega-Xis: Yeah, I don't think that there is anyone stronger than that guy was.
??? (Sirius): That may be true... But it was his pride that made him such a difficult pawn for me to control.
Omega-Xis: Who is that!?
??? (Sirius): Gahaha...
MegaMan: Show yourself!
??? (Sirius): Gahaha... Before that... I'd like to congratulate you, Mega Man. I was very interested in your profile data when I found it in Meteor G. Its analysis on your abilities was right on the mark. However... The trials ahead will push you to your limits. If you were to make it all the way to me... I would be most impressed. And I would be thrilled to add you to my collection. ...But for now, adieu.
MegaMan: We won...
??? (Sirius) Gahaha...
??? (Sirius) I see that you've eliminated all of my "R"s... I guess there is nothing left for you to do but to come and visit me.
Omega-Xis: What, you too scared to come to us?
??? (Sirius) If you come to see me, then I'll add you to my collection. I'll put you right next to Planet FM. See you soon. ...
Sirius: Gahaha... Welcome, Mega Man.
MegaMan: So you're Sirius! How dare you...
Sirius: It has been a long time since I last had a guest. Oh, about... 100 years or so. Yes, that sounds right.
Omega-Xis: Hey! Stop talking to yourself and pay attention for once!!
Sirius: ... I don't need that rude EM being for my collection. Mega Man will look much better on my shelf. So, Mega Man... Stand still, please. It's time to remove your will. Then we'll get you started battling with all sorts of fun EM beings... Your battles are always so enjoyable to watch!
Omega-Xis: He wants to make us his toys... This guy... is insane.
MegaMan: I'm not letting you get anywhere near me! I'll make you pay for what you have done, Sirius!
Sirius: Oh! Fantastic! I just thought of something! Let's set Planet FM as your first battle stage! Do me a favor and go as "buck wild" as you like. I was hoping to enjoy watching everyone on the planet panic for a bit... But I suppose destroying it outright would be fun too. There are so many planets for me to play with.
MegaMan: Peoples lives... Planets... They aren't toys for you to play with. Have you even considered the pain you are putting all those people down there though?
Sirius: Everything here will cease to exist. A black hole has no need for such things as emotions. You should... be happy. You will live forever within the darkness. You will be mine.
MegaMan: I wouldn't call that living! I'd rather not exist!
Sirius: ...I see. Do you think that you might change your mind? Stopping you without causing you any injury would be a bit of a nuisance to me. It will be hard for us to play together with you injured.
Omega-Xis: Do you ever shut up!? You don't stand a chance against us!
Sirius: I have full control over all aspects of this server. You do realize that, right? That gives you absolutely no chance of stopping me. ...But I suppose some children need to be punished in order to learn their lesson.
Omega-Xis: Here he comes, kid!
MegaMan: I'm ready! This fight... Is ours!! Last Battle! Ride On!!
(MegaMan fights and defeats Sirius.)
Sirius: I... I... Like this... ...There are... ways... To go... ...However, Mega Man... You are still but an inch away from deletion.
Sirius: All of my EM powers are being transmitted... To another server. To that... server!
Omega-Xis: For cryin' out loud! Just give it up, already!
Sirius: When the five stars shine together... You two and Earth will see your final days! ...And for extra fun... Here's a gift from me. Enjoy fighting with that rival of yours for all of eternity!
MegaMan: What are you talking about!?
Sirius: Gahaha... Goodbye, Mega Man! Aaaaaahhhhhh!!
- Sirius is presumably named after the star Sirius, also known as the "Dog Star".
- Although he is supposedly the only EM being with the ability to control black holes, the Black Ace Finalize NFB called "Black End Galaxy" also uses a black hole.
- Although he can control black holes, none of his attacks involve gravity-inducing effects or status.
- Sirius seems to admit that Apollo might have been stronger than he was, due to his response to Omega-Xis after Apollo's defeat.
- Sirius' wing attacks parallel that of Funnels/Dragoons/Bits from Gundam.