English Name: Helmeppo
Japanese Name: ヘルメッポ
Birthday: July 16
Age: 20 years old (when joining the Navy) -> 22 years old (when becoming a Lieutenant Commander)
Voiced by: Kouichi Nagano
Appear in: "One Piece"
Gender: Male
Height: 179cm
First Appearance: Chapter 3 of manga, Episode 2 of anime
Position: Lieutenant Commander in the Navy Headquarters
Weapon: Kukri (A traditional Nepalese knife)

Helmeppo is a character in the Japanese anime "One Piece" and its derivative works. He is the son of Navy Colonel Morgan and a Lieutenant Commander of Navy Headquarters. He wields a Kukri knife.

Initially, Helmeppo was arrogant and bossy because of his father's influence. Due to Zoro killing his pet wolf, he agreed to free Zoro after a month, however, he had the intention to break the agreement and kill Zoro, but was stopped by Luffy and Coby. After his father Morgan was defeated by Luffy, he worked as a janitor with Coby in Navy Branch 153. Because of their performance during Morgan's transportation, they joined Marine "Captain Kuro's" troop, dreaming of becoming an Admiral in the future.

Helmeppo, initially relying on his father's influence to act arrogantly, ignores the agreement with Zoro and tries to execute him, but is knocked out with one punch by Luffy. During Morgan's escape, he was taken hostage by his father and thrown into the sea, but was abandoned. He made a solemn vow to surpass Morgan. After that, he joined Captain Kuro's troop with Coby, and through his own efforts, he rose to the rank of Lieutenant Commander. Two years later, he helped Luffy destroy the giant cannon fortress as the deputy of Major Coby. After another two years, he got promoted to Lieutenant Commander and joined the secret special forces "Shuriken".

Before joining the Navy, Helmeppo used to be a weak man with rounded yellow short hair, giving him a look like a mushroom. He wore a gorgeous purple suit, golden necklace, and golden rings. After becoming a Navy sergeant, he grew his hair long and tied it in a ponytail, wore futuristic sunglasses, a plain white shirt, a green vest, and purple trousers. After being promoted to Lieutenant Commander, he started wearing a hat with the word "MARINE" on it and put on the justice coat of a Navy officer.

Helmeppo used to be a coward who exploited his father's wealth and power. He took advantage of people's fear of his father to bully and do wrong things. He threatened to report anyone to his father to kill them whenever there was a slight dissatisfaction from anyone, showing his lack of moral bottom line. Without his father, he was nothing. After being held hostage by his father, he recognized his father's cold-bloodedness and ruthlessness, so he decided to cut ties with him. This made him change from a spoiled brat to a braver person. Gradually, Helmeppo matured into a Navy officer. He self-mockingly said that his past self was like a "straw bag son who was arrogant because of his father".