This was just something I had to get out of my system. Edmund McMillen's two major games featured loads of bosses, some which were absolutely spectacular and some which were...to be honest, kind of bad. Here's my personal choice for the top 5 best and worst bosses Edmund McMillen has ever made.
#5: ???/Blue Baby
I understand that by the time they got to making the Chest level in the Binding of Isaac, Flash was at a breaking point and they couldn't afford to throw lots of new stuff in, but if you ignored the context and just looked at the boss itself, Blue Baby has to be one of the more lackluster final bosses I've seen. He's more of an Isaac Stage 2 than a boss in his own right, with very little difference between the two bosses. Some of his tears are homing. And he sometimes spawns flies. And he's blue...most of the time. That's it. I know that there was no way to avoid it, but I still wish the Blue Baby fight had more significance beyond the fact that it was effectively the final bosses in the game.
#4: Little Horn
If you've seen JonTron's video on his least favorite bosses, you know why he's here. He is effectively nothing but pattern recognition. When you know what's coming, he's easy to avoid, and if you don't know what's coming it's impossible. They might as well have made you click three buttons saying "Left", "Center" and "Right" in a particular order.
#3: Monstro II
This boss is just broken. It was obviously supposed to be more than the "wait to the left or the right until he grins, then dodge out of the way" he became, but he was so easily exploitable that the entire boss fight is an unexciting mess. At least the champion versions are kind of better. #2: Larries Lament
Like Little Horn, I can let someone else do the explaining for this entry - in this case, Northernlion. Like Monstro II, this boss is broken and can be exploited with little effort. However, the effort required is even less than in Monstro II's case and there's less of a penalty for messing up, which I believe justifies putting it above Monstro II on this list.
#1: Mask of Infamy
This boss represents one of the biggest problems I have with the Binding of Isaac - it just seems to be one big item check. If you don't have piercing shots, loads of bombs, bomb shots etc. (and only the bombs are something you have the slightest bit of control over acquiring), your boss fight with this guy can take up to half an hour, but if you do have the right items the mask melts away in less time than other bosses do. Unlike other bosses with weaknesses to certain items, like Larry Jr., this boss comes relatively late in the game and there's quite a few items she's weak to, so using those items feels more like the normal way to defeat the boss instead of the exception. One thing I'll say in this boss's credit is that in the end the amount of damage I tend to take fighting on this boss varies seems to be less bipolar than the amount of time taken to beat this boss, but I still can't find a finer example of throwing yourself at the feet of the arbitrary, dice rolling item gods and hope they don't piss on your face.
This boss had a pretty big impact on me and to be honest it does have that token "I know Super Meat Boy wasn't Edmund McMillen's first game" status, but I don't know whether to put this on my bottom 5 or my top 5 to be honest.
On one hand, the boss was pretty broken. Once you got past the first stage, you got a ridiculous amount of money, and when you combine that with the fact that you can access the shop at any time you effectively became invincible.
On the other hand, the boss was absolutely kick ass. His theme was one of the best I've heard Danny Baranowsky make, and for all its problems it was a pretty thrilling conclusion to a really challenging game.
I think that, in the end, the boss's good points outweighed its bad ones, so the brain boss from Grey Matter gets to go on my Top 5 list.
I didn't know whether to give this to Satan or Isaac. Both were challenging bosses with amazing music, were incredibly challenging and wrapped up a run pretty nicely. In the end I decided I preferred Satan because I fought Isaac so much more that Satan's boss fight still has a bit of novelty to it.
#3: Larry Jr.
Most of the bosses in the Basement have a common factor: once you've figured out their pattern and have a basic grasp of gameplay their attacks become a lot easier to avoid (outside of that Steven/Gemini spray of bullets at the end). Larry Jr. is different because he is so unpredictable that even the most skilled players can find themselves in trouble when fighting this boss. His boss fight emphasizes adapting to the situation and planning ahead as opposed to exploiting some broken feature or having an encyclopedic knowledge of what attacks he will use, so fighting this boss always feels like a new challenge. My main reason for not putting this guy higher is probably because his weakness to bombs and piercing shots are so effective against him that he has a bit of an "item check" issue, although it's a lot better than the Mask of Infamy.
I remember when I first beat Mom. It was absolutely amazing. Mom's boss fight, like Larry Jr's, is chaotic and relies more on being able to adapt to the situation than going through some tactics checklist (I heard of people claiming there's a certain spot where you're invincible to Mom, but I've never figured out where it was). In fact, it's way harder than Mom's Heart / It Lives. While Mom's Heart politely throws monsters at you pretty much one at a time and waits for you to beat them, Mom seems to have no restraint and practically barfs the monsters at you, forcing you to try to choose between avoiding Mom's attacks, avoiding the minor enemy's attacks, and try to shoot either the enemies or Mom herself. It's an absolute clusterfuck and it rewards skill over memory, which is something I feel is needed in a Binding of Isaac boss.
#1: Dr. Fetus
I'm not including Dr. Fetus out of a realization that no other Super Meat Boy boss was on my Top 10 list. I'm including him because Team Meat, through the use of crude graphics and lackluster cutscenes, managed to succeed where other game developers have failed by creating a vilain that the player genuinely hates. Watching Dr. Fetus fall off that platform at the end of the 1st stage of his boss fight was one of the most satisfying moments in Super Meat Boy (I was never able to complete the Dark World boss fight, so I've only seen his ultimate end from watching other people play). I think the reason why I hated Dr. Fetus so much while playing Super Meat Boy was because of the way you transitioned between the levels in the game: after struggling through a mind-numbingly frustating chapter culminating in an extremely difficult boss fight, you are rewarded with a cutscene where Dr. Fetus will nonchalantly press a single button and destroy everything you've worked for before throwing you into an even more mind-numbingly frustrating chapter. It would've been incredibly aggravating if I didn't already know how many chapters I would have to endure beforehand. His tendency to use seemingly innocent women as punching bags and inability to go anywhere without wiping out every single living being in the vicinity also helps. In short, while Dr. Fetus definitely has a lot of levels in badass, he is probably one of the video game antagonists I hated the most.
If there's something I will say against him, however, it's that I would've liked it a lot more if the player didn't start his Stage 2 boss fight already assuming he was dead. It felt a little anticlimatic.