Rebecca "Lupin" Rossellini is the major antagonist introduced in Lupin the 3rd. She is a wealthy businesswoman, heiress, model, actress, and athlete from San Marino, Italy who married Lupin legally after meeting him at a party. She secretly leads a double life as a thief, committing daring heists for the sheer adrenaline rush. The marriage was revealed to be a mere ruse, with Rebecca tricking Lupin III in order to use him as a distraction while she stole a valuable crown for her own thrill and entertainment. Despite this, she still legally has his last name, a fact that annoys Lupin III greatly.

(Source: Wikipedia)