As of 2014, the youngest player to play in the World Cup is Norman Whiteside. He was 17 years and 1 month old when he played in the 1982 World Cup.
Norman Whiteside played for Northern Ireland. His first match in the World Cup was against Yugoslavia on June 17, 1982. The game ended 0-0. He also played in the 1986 World Cup. He played as a midfielder and as a striker. He was 17 years old when he signed for Manchester United in 1982 and remained with the club until 1989 when he moved to Everton.