A Viking chieftain on the other Discworld who, in return for being saved from (i) falling over the edge of the disc and (ii) being flame-grilled by dragons, offers friendship and support to Kin Arad, Marco Farfarer and Silver.
He is small in appearance with red hair with a calulated look in his eye.
It also helps that the Dumbwaiter was reprogrammed to produce first the native Viking brew, and then a potent improvement on the theme.
On Earth known to Kin he discovered and settled the Americas (known to them as Valhalla), with his decendants returning to wage war on Europe.
On Earth, the 'real' Leif Ericson (Old Norse: Leifr Eiríksson) (c. 970 – c. 1020) was an Icelandic explorer known to be the first European to have landed in North America (presumably in Newfoundland, Canada) - nearly 500 years before Columbus. It is now thought that he and his peoples may well have penetrated as far as Minnesota.