"Basil is a Ministry of Magic official, who supervises the Portkey arrivals at the Quidditch World Cup."
From the Story
Discovered in Book 4, Chapter 10, Dress Robes
"A great number of witches and wizards gather around Basil at the place where the Portkeys are located, all clamouring to get away from the campsite as soon as possible. Mr Weasley has a hurried discussion with Basil when the group arrive at the Portkeys, and he allows them to join the queue and take a Portkey back to Stoatshead Hill."