Commander William T. Riker is one of the most beloved characters from Star Trek: The Next Generation. Created to get around the logic problem of a starship captain constantly going on away missions, Riker was meant to be the man of action next to Captain Jean-Luc Picard's man of thoughtfulness. However, it wasn't the addition of his iconic beard that improved the character from the first to second season, it was what was underneath it. In early Star Trek: TNG Will Riker wasn't allowed to smile.
Source：https://www.cbr.com/star-trek-tng-riker-smile/
