Creatures in other worlds: a matter of life or consciousness?

Some people say that there's no life outside of Earth.
But they often forget which are the definitions of life form. I have different definitions in my head of what life form should mean: something that uses energy to evolve, that has means to reproduce itself, and finally die, is already considered a life form to me.
Yes, you may think now of a robot, but they don't "die". They may be shut down and repowered, but that wouldn't be dying to me. Death is the ultimate destruction: you can't recover anthing from it.
If you stick to this definition, "living things" wouldn't necessarily feed or put any kind of garbage out: they could even have a limited life. Moths only feed as catterpillars, but once they reach their final winged form, no more feeding is possible, as they don't have any kind of mouth.
Maybe the most interesting characteristic I added was the reproductive effect. You don't see robots naturally reproducing themselves, they would only do so if ordered. On the other hand, any kind of bacteria has this ability.
Going further, no breathing is necessary either, so organic matter can't be considered a hindrance. You could see life forms made of metal, liquids and so on, and even with some kind of consciousness. That's a dangerous word.
Most of the discussion about extra-terrastrial life is related to this: the ability to recognise yourself as something, or even think about your relation to your environment. And there lies most of our fears: would you be an aggressive creature or a pacific one? I think that is a consequence of two major factors: your own will and your neighborhood. If you are kind in nature, the environment should be tremendously hard to turn you into something furious. The same think can work in the opposite path, although violence is a prevailing tendency, unfortunately.
So, I wouldn't be surprised if we found a new species much like the metallic Cybertronians from the Transformers series, or creatures made of something totally different, as in Evolution, with aliens made out of nitrogen matter.

That's just another cent in the huge vault of speculation around alien life. Contribute too ;)