Nothing like a good ol' apocalypse.
3. Ice-nine
This fictional material is found from the novel "Cat's Cradle". Before you start thinking "What type of lame doomsday device would be from such crazily named novel?!" Hear me out. The book, is based on the fictional co-creator of the atom bomb, and if the atom bomb isn't exploding-ly cool enough for you, I don't know what is.
Ice-nine is a mysterious material that melts at 114.4 Fahrenheit. By the time water begins to boil, this substance is probably just starting to get warmed up. What is ice-nine used for though? Is it used for aerospace engineering for peace keeping missions? Perhaps scientists used such material to protect pilots and astronauts from harmful rays of heat and death?
Oh wait, did I mention that ice-nine has a special trait to act as a seed for water, that can technically trigger water to freeze at room temperature? Yeah, I felt like I forgot to mention that. But how is this "dangerous" you ask? Did the enemy intend to pour thousands of pounds of it over large cities to freeze over like that batman villain? Who said you need thousands of pounds? Why not simply drop a single drop into the ocean, and wait a few days for the entire earth's oceans to freeze?
Nothing like some good ice cream during a ice age related apocalypse.
However, you may be thinking, how does it exactly kill any people? It's not like everyone in the world would be swimming in the ocean at the exact same time right? The best part about this doomsday scenario, is that it would be a slow, ensured death. The biodiversity would be drastically destroyed due to millions of species that lived in the ocean. With such a drastic hit into the eco-system, other land animals such as birds that depend on fish will die as well. Animals that depend on those animals will die, leading to a domino effect, with humans as the final blow.
After that, the decreased temperature would obviously effect the ability for other animals to survive regardless of dependency of certain animals. The temperature alone could kill millions of people lacking shelter and warmth. After that, the world as we know it would be destroyed forever.
For one, there wouldn't be any bunnies.
2. "Divine Bomb"
This doomsday device is from the movie "Beneath the Planet of the Apes", which is the second movie of the series. This bomb, could possibly be the most CGI-friendly doomsday device ever thought of. If you thought a giant laser blowing up the White House was exciting, wait till you hear about this little guy.
The "Divine Bomb" works by igniting the atmosphere on earth. Allow me to say it again, it ignites the atmosphere. What does that mean? It means the entire earth will blow up like the Forth of July, everywhere. The earth would probably look like on giant exploding
How it would probably work is, kill everyone standing in their homes and in streets instantly. Anybody that prepared, and got underground would enjoy a slow painful death. The people underground would slowly enjoy the sweet tan from the sun, as the sun shoots unfiltered radiation onto the earth.
"If I'm going to die, I'm dying in style."
Even if they thought of that beforehand, the lack of life/resources on the surface of the earth will prove to be a problem. Any life that may have survived on earth, would be dead. Any remaining water would very quickly float away to the abyss of space. Depending on the amount of their supplies, they'll slowly starve and die from radiation and lack of bunnies.
1. Ultimate Nullifier
This item isn't some glove you put on that suddenly grants you super strength to allow you to spar with Superman and Wonder Woman. That would be too lame-sauce. The item itself is a simple, small hand/held metallic device with no apparent functionality, due to the fact that people aren't used to the idea of "press here to end everything."
"Press button for instantaneously dance parties"
The device itself has the power to destroy any target the person chooses. I don't mean explode with green flames like in the movies either. The device is capable of destroying the entire universe, if you're thinking small. If you're thinking big, you can technically destroy the "mutiverse", which is the collection of all the universes with alternate "yous". It doesn't simply destroys, it removes.
The item literally "nullifies" anything you can dream of. You can even remove timelines from the history books. Didn't like Benedict Arnold? Bam, problem solved. However, it is so powerful, it can destroy the wielder himself/herself if the person is not capable of using the item. Then again, would you really want to live in a universe, without anyone/anything in it?
Since this item can not only explode the entire Milky Way, but the entire universe, we can probably put this on the top of our list.