How likely are any intelligent beings on other worlds to look like the gray aliens from pop culture? Not very. To find a humanoid form on another world, a whole series of unexpected events would have to been replicated. Early hominids adapted to a particular niche on the savannas of Africa, their upright posture letting them see stronger, fiercer predators at a distance. Under a different environment, having a brain at the top of the body might be a liability, with increased risk of damage by falling but with no great advantage to compensate.