E.T.: The Extra-Terrestrial (1982)
An extra-terrestrial is accidentally left behind on Earth and is befriended by a young boy and his brother and sister. As Elliot attempts to help his extra-terrestrial companion contact his home planet so that he might be rescued, the children must elude scientists and government agents determined to apprehend the alien for their own purposes...which results in an adventure greater than any of them could have imagined.