Yes. There are so many galaxies in the whole universe , Like our galaxy , it's called the milky way. While other's have their different names. A living thing NEEDS liquid water, energy, and a life source such as a comet. There are planets like Earth that can support life such as Gleise 581g, but it is too far away for us to do anything about it. I'm certain that there should be life somewhere out there in a planet that has liquid water, energy (a sun) and a life source, if it has that than it's certain there would be life but i would think it would not be any more than parasites and bacteria. Also, like you said, it would need an atmosphere and a good temperature, if someone says that there might be life on Mars, It cant be real because it doesn't have an atmosphere like Earth's, in fact it only has 1% of it so life on Mars is unable. If the creature is not something small like that, it would need brains, also, atleast one of our satellites would have spotted it. Some kind of reading would have been recorded like a high pitch screech.