Magic Compass

The Magic Compass is an item featured in the animated series and the Legend of Zelda comic.

Animated series
The Magic Compass is only seen in the "Underworld Connections" episode of the "Zelda animated series. It is used to locate the remaining shards of the Triforce of Wisdom.

When Vires manage to split the Triforce of Wisdom into three shards, Link is able to grab one shard while the remaining two go at the hands of the Vires. However, Link shoots a sword beam at the shard that they possess, which defeats the Vires that were carrying the other two pieces into the Underworld. Using the Magic Compass, Link and Princess Zelda venture into the underground to locate the two Triforce shards that were dropped by the Vires and thus reunite the Triforce of Wisdom.

The Legend of Zelda comic
In the Legend of Zelda comic, much like in the animated series, the Magic Compass is used to locate the Triforce of Wisdom. In Missing in Action, Link uses the Magic Compass to track Princess Zelda, who has taken the Triforce of Wisdom to leave Hyrule forever and thus impede Ganon from ever obtaining it. Link uses the Magic Compass once again in Queen of Hearts when the Triforce of Wisdom is stolen, which leads them to find out that Queen Seline took it.