Mimir

Along with their pal Mimir — the disembodied head of “the smartest man alive” — they set out on an odyssey spanning multiple dimensions.

Another well beneath another root was the Well of Knowledge, guarded by Mimir the Wise.

Heimdall will blow the Gjallerhorn, the horn that once was Mimir's, and he will blow it with all his strength.

Odin greeted the kind old giant, and said, “Oh, Mimir, I have come from far-away Asgard to ask a great boon!”

But under the root that stretches out towards the Frost-giants there is Mimir’s Well, in which wisdom and wit lie hidden.