|Creator||Lady of the Lake|
|Owner||King Arthur (formerly)|
Excalibur is a magical sword that any wound it inflicts can not be healed by most means. Excalibur can be used to release magic into the world when inserted into the Stone of King Arthur, which will charge the Ley lines with magical energy, draining and destroying Excalibur in the process.
Sentience: Cal has a mind of his own, and, as such, can choose who he will obey. He generally displays the intelligence and loyalty of a bright dog, as well as making compatible whining noises.
Flight: Cal can hover in mid-air for as long as he wants to.
Leyline Unlocking: Cal will, when inserted into his stone, restore magic to Earth, by charging the ley lines that carry it.
Crown of King Arthur : Any person, good or evil, who has said Crown is able to force Excalibur into submission.
The Stone of King Arthur: If Cal is inserted into its stone again, the magic contained inside it will flow into the Earth, causing it to; melt and disappear.
- "The Librarian: Quest for the Spear"
- "The Librarian: Return to King Solomon's Mines"
- "The Librarian: The Curse of the Judas Chalice"
- "... And the Dark Secret"
- "... And Some Dude Named Jeff"
- "... And the Trial of the One"
- "... And the Echoes of Memory"
- It was mentioned by Judson to Flynn that only those worthy could pull Excalibur from the stone.
- According to Flynn, wounds inflicted by Excalibur will never heal. In most versions of the Arthurian myths, the scabbard of Excalibur can heal any wound.
- Excalibur is one of the most powerful artifacts in the Library, as it was able to contain all magic on Earth for centuries, until shortly after the series started.
- As is common in modern storytelling, the separate myths of the Sword in the Stone and Excalibur are here conflated.