Tengen Toppa Gurren Lagann/Nightmare Fuel

For such an awesome, funny, and heartwarming show, Tengen Toppa Gurren Lagann has some scenes that are pretty darn scary.

• The battle against multi-faced arm-sprouting huge anti-spiral ships. The opening mouths and eyes when the true strategy comes to surface (quite literally) will haunt viewers until the Grand Finale
• Also: "Don't touch that or I'll GOBBLE YOU UP!"
• Hearing Kamina's scream right after he was horribly mutilated by Thymilph's spear in Episode 8 can be pretty terrifying.
• Still... Spinning...
• The results of Simon's Heroic BSOD following Kamina's death. Seeing the Cute Shotaro Boy turn into The Berserker who vanquishes Mooks with a No-Holds-Barred Beatdown, and is channeling so much Unstoppable Rage that his mech actually pukes and shuts down is... rather unsettling, to say the least.
• The Ashtunga can be rather creepy.
• What the Anti-Spiral did to Nia, He pretty much mind raped her with a big old The Reason You Suck speech, and then started to kill her by extending a long, white arm and disintegrating her while she screamed in agony. And in The Movie, he actually MOUNTED HER WITH THAT CREEPY SMILE AS SHE SCREAMED OUT SIMON'S NAME. Guh. (NSFW)
• The scene where we see the AS ships with faces all over them, and said faces suddenly open their mouths and eyes real wide and start firing missiles out of the former.
• The Anti-Spirals are full of this trope. A Hive Mind with god-like powers that has committed the near-omnicide of Spirals, their rap sheet includes: ripping off Majora's moon trick; having digital drones that can Zerg Rush you: inserting Messengers within every Spiral Race that don't even know of their true nature until the time is right and could be ANYONE, even one of your loved ones; being able to trap their enemies in alternate realities that can be their greatest dream or (presumable, even though it never happened in the series) their worst nightmare; and they have an avatar who looks like Slendy that has naughty tentacles and isn't afraid to use them. Oh, and the scariest thing about them? They think they're doing the right thing, even as they cross the Moral Event Horizon over and over and over again. The only thing that prevents them from being one of the most depraved Complete Monsters in all of fiction is that they are truly convinced that they're the good guys; even then, that may not be enough to redeem them. Why? Because instead of just taking the easy way out and using their god tier powers to Kill'Em All in one blow, they prefer to defeat their enemies by sending them over the Despair Event Horizon - and they enjoy it.