We currently know of no other planet (besides the Earth) that has life on or in it. But NASA is looking for life on Mars for example, by 'following the water.' That is, if we see signs of liquid water, even in a past time, there is a chance that Mars had some kind of life form similar to what we find here on Earth, microscopic perhaps, we don't know. The MER mission, the twin rovers that landed and studied the soil and surface of Mars found conclusive evidence of the existence of water on Mars a long time ago. So, maybe there was some kind of life form, now extinct, we don't know.