Dr. Vegapunk is the leading scientist of the SSG and in the employment of the Marines. His work includes discovering the secrets and uses of seastone, the secrets of how Devil Fruit powers work, the co-discovery of the Lineage Factor and its applications, the creation of the Pacifista and Seraphim, and various other scientific achievements that are said to be at least 500 years ahead of current technology. He hails from the technologically advanced Karakuri Island and currently resides on Egghead, where his laboratory is located.

Before being employed under the World Government, Vegapunk had been the director of an outlaw scientific research team known as MADS, where he worked alongside other notable scientists such as Caesar Clown, Vinsmoke Judge, Queen, and Buckingham Stussy. The team was eventually arrested, and Vegapunk was later integrated into the Marines as its head scientist after MADS’ dissolution. This was until Vegapunk became enemies with the World Government once more, when the World Government dispatched CP0 in attempt to kill him.

He and his satellites are major allies to the Straw Hats during the Egghead Arc.

(Source: One Piece Wikia)