15th World Science Fiction Convention

Loncon I, the 15th World Science Fiction Convention
GenreScience fiction
Dates6–9 September 1957
VenueKing's Court Hotel
Location(s)London
CountryUnited Kingdom
Attendance268

The 15th World Science Fiction Convention (Worldcon), also known as Loncon I, was held on 6–9 September 1957 at the King's Court Hotel in London, United Kingdom. It was the first Worldcon held outside North America.

The chairman was Ted Carnell.