This is a rather philosophical thought I had for the past few days about the various doomsday devices ever devised in Science fiction. I'm not familiar with all Sci-Fi doomsday devices so I'll just stick to those I've seen. Granted this might not be all of them either, just the most infamous.
In Star Trek Voyager we have the species 8472 bio-ships:
Next we have the doomsday machine from the ST the original series:
Following, we now have V'Ger from ST the motion picture:
Now, for Star Wars: A New Hope we've got the Death Star:
From Return of the Jedi we also have Death Star II:
And finally, from The Force Awakens, we have Starkiller Base:
Now, after seeing all these puppies in action, which one is the most dangerous doomsday device? After mulling it over in my head the answer came to me--a lack of governing by intelligence (people). All doomsday devices are governed by beings. Wills to decide whether or not to destroy a terrestrial body. While V'ger doesn't have people governing it, it still has an intelligence, and a will to decide whether or not to render a world dead. All of the above seems to qualify for having governing minds behind them--except for one. Star Trek's The Doomsday Machine. It comes across to me as being the most dangerous planet killer device ever created because it does not have a governing intelligence (people) behind it. It is a fully automated weapon that has only one primary function: To destroy worlds and digest the derbies for fuel. It does not discriminate on what type of planet to destroy. If it's there, it's food--lifeless or otherwise. As long as there are planetary bodies to ingest the machine will function indefinitely. It is an out-of-control weapon right from the get-go.