Codex Gigas

Depictions of the devil were everywhere in medieval times, but the early 13th-century Codex Gigas – the largest medieval manuscript in existence – stands out. The story goes that a Czech monk, challenged to copy out a whole Bible in one night or spend the rest of his life walled in his cell, supposedly sold his soul to the devil to accomplish the task. The almost two-foot-tall picture of Satan, said to have been completed by the grateful monk, has a peculiar menace down not only to its sheer size, but also to its piercing eyes and claw-like hands, stretching out as if to drag you in.

From: http://www.guardian.co.uk/culture/gallery/2010/sep/19/ten-best-devils#/?picture=366807333&index=4

More here: http://en.wikipedia.org/wiki/Codex_Gigas
http://www.kb.se/codex-gigas/eng/