A thyle (OE þyle, ON þulr) was a member of the court associated with Scandinavian and Anglo-Saxon royalty and chieftains in the Early Middle Ages, whose precise role is uncertain but probably had to do with the preservation of knowledge of the past and the judging of present statements against it. […]
The Old English term is glossed as Latin histrio “orator” and curra “jester”; þylcræft means “elocution”. Zoëga’s Concise Dictionary of Old Icelandic defines þulr as “wise-man, sage,” cognate to Old Norse þula (verb) “to speak” and þula (noun) “list in poetic form”. The Rundata project translates þulr as “reciter”. From this it appears that the office of thyle was connected to the keeping and reproducing of orally transmitted lore like the Rígsþula, “Lay of Rígr”.
[…] Unferð holds the role of thyle in the poem Beowulf; it has been suggested that he was also the scop who is mentioned reciting poetry at the feast. It might be seen as a legitimate function of a guardian of the knowledge of the past to challenge boasts, judging them against the heroic past. This may have played a role in preserving the luck of the group.
Source: Thyle – Wikipedia