you're in a group of 6 people, only 5 of them are your friends the other person just follows the group all the time, he's in that case the hanger-on
a hanger-on is a person often without any friends who follows around popular groups in for example school or at parties/clubs etc
"you're in a group of 6 people, only 5 of them are your friends the other person just follows the group all the time, he's in that case the hanger-on" What is the definition of "hanger-on"?