The beautiful Leopard Slug, Limax maximus, was observed several times during a short stay in Aberdeen, Scotland, on Sep. 2011.
It is one of the largest land slugs, reaching up to 20 cm (8 in) in length. The ones I observed were less than half of that size.
As most land snails and slugs, this species hides during hotter hours or when dry, but will show up quickly after some rain, as it was the case here in at least one occasion.