Which Swedish king does Beowulf support against Onela?

Beowulf supports the Swedish prince Eadgils against his uncle Onela.

Eadgils and his brother Eanmund flee to the Geats after their uncle Onela takes the Swedish throne. Their father, Ohthere, has died, and the brothers’ claim threatens Onela’s rule. Heardred, Hygelac’s son and king of the Geats, gives them refuge.

Onela attacks the Geats, killing both Eanmund and Heardred. Beowulf then becomes king and later helps Eadgils make war against Onela. The poem says Beowulf provides Eadgils with warriors and weapons, enabling him to defeat his uncle and gain the Swedish throne.

Eadgils is sometimes identified with Aðils in Old Norse tradition. Later Scandinavian stories also preserve the conflict with Onela, though they give Beowulf’s role to Danish rather than Geatish allies. That variation can cause confusion when comparing the poem with the sagas.