King Arthur of the Seven Seas!

Arthur & Excalibur

What's that? You mean that's not the title of the latest Aquaman movie starring Jason Momoa?!

Could have fooled me! I mean, let's look at the evidence:

• The young prince growing up away from his throne, for his own safety - check
• Grizzled mentor who tries to prepare him for the throne, but doesn't always tell him the whole truth - check
• Prince Arthur - check
• A quest - check
• A Lady in the Lake - well, a Queen in the Sea at the centre of the world, close enough! - check
• A magical sword in a stone - ok, it's an all-powerful trident in a fossilized skeleton's hands, but close enough - check
• An impressive (future) queen who stands by her (future) king - check
• "One true king" - check
• Main enemy is a family member - younger brother vs nephew? We'll take it! - check

See what I mean?!

Lady in the Lake

Guinevere

Merlin

Mordred