The Old English poem "Beowulf" opens with Grendel's attack on King Hrothgar's mead hall. There are several reasons behind the attack. The first is simply that Grendel is an evil monster. The second is that Grendel is hungry. The third is that Grendel hates the noise of the soldiers, and also envies their happy life.

The second instance of envy we encounter is somewhat more positive in the challenge that Unferth poses to Beowulf. What we see in the type of envy that exists among the heroic figures in the poem is an element of what theorists such as John Miles Foley and Walter Ong describe as the "agonistic" element of traditional epos, in which heroic characters strive with each other for fame; this envy, while it can turn bitter, and lead to internecine squabbling, it can also been seen as a spur to great achievements.

Revenge is an especially important part of the Grendel story arc. After Beowulf injures Grendel, Grendel's mother decided to take revenge on the Danes for killing her son. Beowulf than kills Grendel's mother in revenge.