poster child
noun [ C ]
ukusplural poster childrena person or thing that is seen as a typical example of something:
a poster child for sth He is the poster child for excessive chief executive compensation.
a poster child of sth The company has been the poster child of denial among those convinced of global warming.
a child with a particular illness or disability whose picture is on posters to raise money to help children who have the same illness or disability:
As a March of Dimes poster child, she was a bright, carefree child who refused to let her disability get in the way of playing like the other kids.