Sanjuan Wolf

San Juan Wolf is a colossal giant who is a member of the Blackbeard Pirates. Known as "Colossal Battleship" for his size, he was originally one of the legendary criminals who was given a life sentence in Level 6 of Impel Down, where their crimes were so atrocious they were effectively erased from history itself. He was initially mentioned briefly by Emporio Ivankov.

Appearance
San Juan is an unbelievably-enormous giant, much bigger than Oars or Oars Jr. In fact, he is so big that he appears to be roughly the same size as Marine Headquarters at Marineford and is thus the biggest known giant to date. His head is shaped like an Onigiri, and his facial features include round eyes with dark lining around them, along with mark-like eye-lashes, similar to those found on Franky's, that points downwards.

Personality
Despite being known for committing crimes that caused his existence to be erased from history, he seems to have a playful attitude, as seen when commenting that he was found when he was trying to hide behind Marine Headquarters at Marineford. He is also quite shy, as he acts scared when people realize who he is and continues hiding while the rest of the crew fights Whitebeard.

Abilities and Powers
His abilities have not yet been shown, but he was powerful enough to be contained in Level 6 of Impel Down when caught by the World Government. Presumably he shares traits with other giants, including Super Human Strength, though to what degree is unknown.

Imprisonment in Impel Down
San Juan Wolf was once one of the most feared criminals in the world, and is noted to be the only known giant of his size, but was eventually caught by the World Government and sentenced to life in Impel Down, Level 6, where he was effectively erased from history, appearing as a huge giant in a cell near Ace's. Only a few people such as Emporio Ivankov knew who he was.

When Blackbeard and his crew came to Impel Down however, he was broken out of his prison cell by them along with Catarina Devon and Basco Shot. He and his fellow prisoners then joined Blackbeard's crew and went to Marineford.

Marineford Arc
He was seen alongside the Blackbeard Pirates and fellow criminals, all of whom have been recruited into the crew, and are now at Marineford to watch Whitebeard die.

Trivia

 * He is so far the third largest creature shown in One Piece, only behind the unknown being that was shown at the end of the Thriller Bark arc, and Laboon.