This slug has many popular names, spotted leopard slug being one of them.
More information: http://en.wikipedia.org/wiki/Limax_maximus
It is the most commons slug in the toad’s garden, and it’s a blessing. It seems to be territorial, keeping other slugs, also invasive “killerslugs”, at a distance. Since the latter is spreading rapidly in Denmark, and have arrived to the neighborhood, next year the leopards must show value for my affection, please !
My friend Brian from Gourmethaven took a snapshot of the leopards attack on the “killerslug”, where you can see the fresh white wound. http://www.gourmethaven.dk/artikel/vis.php?id=204