Identity in the world of Beowulf is made up of two main components - heritage, and reputation. Heritage is the sum of the deeds of one's forbears and the bloodline of one's ancestors. Reputation is the sum of the deeds of oneself. Beowulf's fame and identity are both made up of deeds performed by himself and his ancestors.
Beowulf introduces the reader to a world where every man is known in relation to someone else. Even Grendel is introduced to the reader as being "conceived by a pair of those monsters born of Cainpunished forever for the crime of Abel's death" (105-108) Grendel is known firstly by mention of the deeds of his ancestor, Cain - it is only in the following lines that the deeds of Grendel himself are told. Beowulf himself is first introduced to the reader as "Beowulf, Higlac's follower and the strongest of the Geats", (193-194) and subsequently introduces himself as the son of "a famous soldier, known far and wide as a leader of men". (261-262) He is talked of by the Danes as "a mighty warrior, powerful and wise", (370) and a man with "thirty men's strength". (380) This is even before Beowulf and Hrothgar have met - clearly Beowulf's fame is such that it precedes him a fairly long way.
For the most part, characters do not speak without first introducing themselves in relation to their ancestors and each introduction of a character by the narrator necessitates a new introduction of their ancestral heritage. In the world of Beowulf, then, the identity of the characters is the sum of both their own deeds and that of their ancestors, and there is a great deal of emphasis placed on the importance of kinship bonds. The characters in the story take pride in ancestors who have acted with honor. The honor of their ancestors adds to their own glory, and they are also concerned with living up to and exceeding the reputations of their ancestors. Thus Beowulf is often described according to his relationship with others: as "Edgetho's brave son", (628) and "Higlac's follower". (758)
In Beowulf, heroic deeds are the primary means by which one establishes a reputation and an identity. Ancestral heritage is an important consideration - not only does it help establish identity, it provides role models for future generations - but it is a secondary one. In the beginning of the poem, Beowulf is variously described as "greater and stronger than anyone anywhere in this world" (195-196) and "loved by the Geats" (203). Heroic feats he has performed have already established his reputation. The first Dane he meets upon landing his boat recognizes that here is a man who is greater than "all the men on earth". (248)
Beowulf seems often concerned with the doing of deeds for the fame and glory they will give him. This is an important concept, since the pagans do not believe in an afterlife. Beowulf does not believe he will ascend to heaven and spend eternity with God. What he does believe is that by accumulating a store of heroic deeds in his earthly life, his reputation and fame will live on after he dies: his descendants will introduce themselves in relation to Beowulf, and his legendary deeds will be spoken of for hundreds of years. Reputation is the one thing that will endure after this death - it is his key to achieving immortality. This is how Beowulf will live on after his death, and in Beowulf's world, death is a constant