Stalker

Lieutenant Junior Grade Stalker (ストーカー中尉, Sutōkā Chūi) is a Marine on Vice Admiral Momonga's crew. He was the one to report on Boa Hancock after the stowaway Monkey D. Luffy yelled out "I'm stuffed". Stalker thought it was Hancock, and since the other Marine soldiers thought that Hancock would not be so unladylike, they bet that if it was her, they would have Mohawk hairstyles. When Hancock embarrassingly took the blame, the Marines had Mohawks.
First Appearance: Chapter 524; Episode 421

Source: