do aliens exist???

[The Anarchy Angel]

But! Yoda and PuPu so cuuuute! I want one...two of each! I'ma make an alien farm!

[T-MaN]

I'm an alien.

Yes, I believe in them. We can't surely be the only life forms in this grand universe.

[Jess]

The universe is so big, if we can live then I guess there is others living amongst us.

[Sepho]

The Earth is one tiny speck in the galaxy, which is in turn one tiny speck in the universe, so to think that we're the only planet in the entirety of the universe whereupon there are living organisms is just a silly idea, when you think about it. We could be known about by a multitude of planets, the inhabiting species of which may regard earthling humans as a primitive race. It's almost arrogant to think we're the only thing in all of space. So if an alien describes any organism not native to Earth, then yeah, I believe in alens.

Theoreticaly, Mars at one point could have supported life, but it has never been confirmed.

I don't think the theory is at all farfetched. You've got the right idea about evolution. Mars may be uninhabitable by the species of Earth, but that's only because we've adapted to the specific conditions of this planet throughout our evolutionary history. Organisms adapt to their surroundings in order to survive; that's something we all learn early on in school. That idea can likely be applicable on a larger scale if you think of each planet as, say, a different ecosystem.

[SomethingBig]

I'm an alien, so I believe in 'em.

As for extraterrestrials, it'd be ignorant to say that the earth, among the billions of galaxies that exist in the perpetual expanse of the universe, is the only planet with life. I'm certain that there's life outside of earth, whether they be single-celled life or beings that have accomplished light-speed and time travel. Heck, maybe even both. They've already discovered single-celled organisms on the moon(or was it Mars?).