Santa Claus

Santa Claus, also known as Saint Nicholas, is a legendary figure associated with the holiday of Christmas.

According to legend, on every Christmas Eve Santa travels around the world distributing presents to the good children of the world. He flies around the world thanks to his reindeer. They land on rooftops where Santa enters the home.

Benjamin Grimm was aware of the figure and the legend. When Black Panther infiltrated the Four Freedoms Plaza, Ben reasoned that since it was not Christmas the person was not Santa nor his reindeer.

Background
Santa Claus was not seen, merely briefly mentioned by Thing.