Is there any proof other than myths and rumours that other life forms exsist?

Question: Is there any proof other than myths and rumours that other life forms exsist?
- Keywords:
  alien,
  life,
  myth,
  proof,
  rumour
Asked by maxie to Tianfu on 28 Jun 2012.
- Tianfu Yao answered on 28 Jun 2012:
  
  Do you mean the unknown creatures? This is not my major, unfortunately. But I guess the aliens do exist, since there lots of proof indicating they have come to the earth before.

Question: Is there any proof other than myths and rumours that other life forms exsist?