The Pardoner in "The Pardoner's Tale" personifies death as an "old, old fellow." He meets three drinkers while they are out searching for him--death.
The three are drinking in the tavern in the morning, before 9 a.m., and when they hear that still another person--a friend of theirs from the past--has fallen victim to death during the current plague, they vow to kill death. They meet him on the road in the form of the old man. They are extremely rude to him, and he sets them up for their deaths--to meet him literally.
They repeatedly swear their loyalty to each other. The Pardoner/narrator says at one point:
They made their bargain, swore with appetite,
These three, to live and die for one another
As brother-born might swear to his born brother.
Of course, death gets its way when the three betray each other and are killed by one another. The personification of death as the old man forms one part of the tale's allegory. This is an often-told tale that Chaucer makes his own by adding irony. Not only do the three kill each other after swearing loyalty, but the tale, which demonstrates that "greed is the root of all evil," is told by the Pardoner, who uses it to separate listeners from their money.
In this tale, the Pardoner is telling the story of some men who were drinking late at night in a tavern. They hear a corpse being carried to its grave outside. They are told that the corpse was a friend of theirs who died while drinking.
An unseen thief, called Death, came stalking by,
Who hereabouts makes all the people die,(75)
And with his spear he clove his heart in two
So death is personified as a thief carrying a spear.
When the three men hear this, they decide that they are going to go out and kill death. They swear to be blood brothers and stand up for one another until they manage to kill death.