Lord of the Coast

The Lord of the Coast is a Sea King who inhabits the waters near Foosha Village.

Appearance
Unlike many other Sea King, Lord of the Coast is fairly small in size (relatively speaking); however he is still quite large in comparison with most other sea monsters in the One Piece world.

His appearance is similar to a large oversized brown eel with red eyes and blue fins.

Like other Sea Kings, Lord of the Coast is very aggressive and fierce in nature.

History
He was first seen when he ate Higuma, who was in a small rowing boat, shortly after Higuma threw Luffy into the water. He then tries to eat Luffy, failing to do so and instead just managing to bite off Shanks' left arm. He is scared away then by Shanks, who stares him down using his Haki.

Ten years later, as Luffy leaves his hometown to start his journey as a pirate, the Lord of the Coast tries to eat him again. Luffy promptly knocks him out with a "Gomu Gomu no Pistol".

Anime and Manga Differences
The anime didn't depicted Luffy punching Lord of the Coast while leaving home during his original backstory. Luffy's past was revealed in a flashback which pointed out small details such as this.

However Luffy is featured knocking him out in the original opening for the series (We are!) as well as One Piece: Grand Battle! Rush!.

It was finally show in the anime series near the end of episode 504, when the rest of Luffy's backstory was revealed. Luffy's stance in the episode is closer to the manga than in the opening, with his foot sticking up and his left arm holding his right, whereas the opening has his foot on the edge of the boat and his left arm pulled back.

Merchandise
He was issued alongside Shanks and Luffy in a One Piece Block Figures set featuring the Straw Hats and their past mentors/loved ones.

Trivia

 * Lord of the Coast was both the first Sea King and the first sea monster to be featured in the series.
 * In Romance Dawn V.1, instead of Lord of the Coast, a shark was featured biting off Shanks' arm. In some older fan-made scans, he is still named as a "shark" and not a Sea King despite clearly not being a shark, however until the crew tries to enter the Grand Line the greater identification of Sea Kings were unknown at the time.