"Whatever you are, you just made a terrible mistake! Us Limaxes live for the heat. Why do think we came to the desert in the summer?" The Limax
"Please. No more!" Zombozo. He got better
"You little human meatbag. Nobody controls Slix Vigma! Nobody!"
"Resistance is futile. For even if you destroy me, you can not possibly stop the billions of my spores I am about to release into your atmosphere." The Fungal Brain
"Think of it, Ben. With the power of the Watch, and your DNA, I will be unstoppable." Ghostfreak. He Got Better
"The battle is not over, so long as one of us still stands." Ishiyama. Upgrade made him better
"We will not be stopped!" Coach Finn
"You are giving me a headache." S.A.M.
"Dr. Viktor, I am your superior." Dr. Shueman... possibly?
"Foolish children. No!" Ghostfreak. During the Time Skip, he got better
"You... you are Ben Tennyson. You can do anything." Magister Labrid
"You wouldn't dare! You would be destroyed, and your offspring." Highbreed
"Em-Emperor Milleous, have mercy!" Frolic the Incursion
"" Dr. Joseph Chadwick... possibly?
"Please be all right." Tini... possibly?
"I... can't... let you... win!" Ultimo... possibly?
"What'ja gonna do now, tough guy?" Ben/Chromastone. He regenerated into Diamondhead
"All the more reason for you to gather the other humans and leave this place. Go!" Highbreed soldier
"Ben... Tennyson... NO!" Ghostfreak
"I didn't have no change." Rhomboid Vreedle clone
"We don't want it anymore. So it's your problem now." Octagon Vreedle clone
"I really hate those guys." Incursion Commander Sang-Froid
"Do what you can. I trust you." Alternate Timeline Ben
"No, the stars... are still aligned. There is still time. But, I am too weak... to continue. Ben, please." Sugilite. He got better
"I'll always be with you, Max. You tell my wife and son... I love them." Devlin Levin
"No." Ragnarok... possibly?
"This is a clear violation of code T22 Dash-AAAAAAAAGGGGGGGHHHHHHHHHH!!!" Magister Prior Gilhil
"" Foreverduke838... possibly?
"You knocked my block off." Computron
"It... hurts..." Andreas. He got better
"When I get out of these bonds!" Ra'ad. He got better
"What happened? How did I-" Bivalan. He got better
"" The Sentinel
"Don't argue, kid. Run!" Kwarrel
"We did! I did!" Elena Validus. She got better
"" The Synthroid
"No! You can't!" Pierce Wheels
"Ben Tennyson! You have made a dangerous enemy this day. Mark my words, YOU HAVE NOT SEEN THE LAST OF MIZARU!!!" This from villain of the week Mizaru... who is seconds later eaten by a giant worm thing fought earlier in the episode. The gang stares stunned for a moment before Gwen says "I think we've seen the last of Mizaru."
"Sustilance. We must have more garbage. We will take what we need!" The Garbage Monster... possibly?
"" Adwaita. He got better
"Wow. Harder... than I thought!" Ben Tennyson. He got better
"Tennyson! I need some metal over here!" Kevin Levin. He got better
"No." Gwen Tennyson. She got better
"I'm sorry I wasn't there when you needed me, Hope. But I can't stay here knowing my life was bought, at the cost of so many others. Goodbye my daughter, I love you." Spellbinder, before returning to the dead
"May Diagon curse you!" Conduit Edward
"It was an honour... to be your squire..." Winston
"What wizardry is this? Clouds can not protect you from my wrath!" Sir George
"But my substance is power!" Diagon... possibly?
"Huh! I bet that is what y'all call your basic countdown to destruction." Original Rhomboid Vreedle
"Clearly we did not think this through." Original Octagon Vreedle
"How do you shut this thing off?" Original Emperor Milleous
"Huh, Alien X! It is real!" Original Rook Blonko
"So, this is Alien X, huh? Great, we're toast." Original Argit
Technically, the rebooted universe is a new one with everything but Mr. Smoothy identical, with Ben the only survivor of the old one. This has never been spoken of again.
"While Ben Tennyson steals the spotlight. As usual." Mazuma
"You there! Step away from the fossils!" Galvanic Mechamorph Museum Guard
"See, what goes around comes around." Feedback. He Gets Better.
"Curse you, Ben Tennyson!" Malware
Secret of the Omnitrix
"You're not leaving here without me!" Lepidopterran Prisoner
Race Against Time
"He knows... he knows... Good luck, my son. You'll... need... it..." Constantine Jacobs
"No! It's not my time!" Eon
"You were a fool to transform into a drone. I can easily defeat a puny drone!" The Decoy Queen of the Hive