Cohen the Barbarian is the Discworld's greatest warrior hero, renowned across the Disc for his exploits rescuing maidens, destroying the mad high priests of dark cults, looting ancient ruins, and so on.
On his first appearance in the series he is already an old man, but still tough enough to handle anything the world can throw at him; his opponents often underestimate him because of his age, realising too late that a man who does for a living what Cohen does and nevertheless survives to such an age must be very good at it indeed.
The greatest problems Cohen face come from outliving the heroic age, and finding himself in a civilised modern world where great battles and astonishing rescues happen rarely except in stories. One of the rare Discworld short stories tells of Cohen setting out to slay a monster, only to end up reminiscing with it about the good old days when things were black and white and everyone respected the traditions.