What is Willy a nick name for?

WilliamA short form of William, from the Old Norman French Willaume, which is derived from the Old High German Willehelm, a compound name composed from the elements willeo (will, determination) and helm (protection, helmet): hence, "resolute protector." William is the most popular name introduced to England by the Normans.

What does Willy mean in slang?

penis

noun. wil·​ly ˈwi-lē variants or less commonly willie. slang. : penis.

What is the English name for Willy?

Willy as a boy's name (also used as a girl's name), is related to the Old German name William, English name Willie and Old English name Willis.