To the best of my knowledge, I've never seen an alien. However, I have seen a "flying saucer" so to speak. It was only there for a second. I couldn't prove I saw it, but I know I did. Of course, no one believed me. And that's ok because I'm confident enough in myself that it's not necessary for anyone to believe me.
Here's what happened. I was invited by a neighbor's daughter to attend a Tupperware party. This party was in a different neighborhood so I caught a ride with other neighbors who were also invited. We were there for a few hours; some attendees were drinking, but I didn't drink much back then so I only had coffee.
When it was time to leave, we filed out the front door and down several flights of outside steps to the car which was parked right out front. I was waiting my turn to get into the back seat. As I began to duck into the car, I quickly looked back over my shoulder and up into the sky because it suddenly occurred to me that I heard a humming sound that, under normal circumstances would have seemed like normal city noise, but it was midnight and the noise suddenly sounded out of the ordinary to me.
I looked back as I was getting into to back seat so it was just a second that I had before I was sort of pushed into the car by the person waiting behind me. What I saw was incredible and by the time I sat down and got situated to make room for the other person to get in, not only was it gone, but the noise had also stopped.
I'm yelling to everyone in the car, "Did you see that?" At the same time I'm looking out the back window to see if I could still see it. Naturally I was the only one who seen anything; no one else even heard the humming sound. They thought I was drunk, which is pretty good since I only drank coffee.
What did I see? I saw a very large white disk floating above the houses. It was so large that I really only saw part of it because the rest was out of view. I don't think I was meant to see it because that quickly it was gone. It was like a really large moon laying so close to the earth surface that it looked like it was trying to land on the rooftops. I'll never forget it, it was very surreal. I've never seen anything like it since....no little green men running around or trying to experiment on me. But I DID see the disk.
I don't know if I believe in beings from other planets. But it would seem very presumptuous of us to think we're the only beings in the universe. Frankly, I'm hoping we someday find intelligent beings somewhere out there. Because it's getting increasingly more difficult to find them here.