In ice hockey, the captain is the player designated by a team as the only person authorized to speak with the game officials regarding rule interpretations when the captain is on the ice. At most levels of play each team must designate one captain and a number of alternate captains who speak to the officials when the captain is on the bench. Captains wear a "C" on their sweaters, while alternate captains wear an "A".
Sidney Crosby, wearing the "C" as captain of the Pittsburgh Penguins
Captains Nicklas Lidstrom of the Detroit Red Wings (right) and Ryan Getzlaf of the Anaheim Ducks (middle) talk with a referee
Evgeni Malkin in 2017: the "A" is commonly on the left side of the jersey (from wearer's perspective)
Terence Joseph James O'Reilly is a Canadian former professional ice hockey right winger. He played for the NHL's Boston Bruins and featured in three Stanley Cup Finals. He was one of the most effective enforcers in NHL history. For this reason he was called "Bloody O'Reilly." O'Reilly was born in Niagara Falls, Ontario.
O'Reilly with the Boston Bruins in 1978
O'Reilly charges into the stands during an incident at Madison Square Garden in 1979
O'Reilly in 2012