No. UFOs with an extra terrestrial origin do not exist. I reckon alien lfie exists somewhere in the universe, and even the most conservative estimates applied to the Drake equation suggests that there should be many other advanced races in our galaxy, even though intelligent life would be rare (simply because the numbers we're dealing with are so huge). However, this is something that the human race is still fairly ignorant about. We barely know of any rocky exoplanets, let alone ones that could harbour life. Not to mention the recent findings by Nasa that demonstrate that life does not have to contain the same kinds of chemicals as us, which throws everything off again.
So in short, I reckon life exists elsewhere, but I also think it's unlikely that they've reached us, and to be honest we have no idea what they are or where they might be.
