white hat - Wiktionary, the free dictionary

From Wiktionary, the free dictionary

white hat (plural white hats) (idiomatic)

1. A good person; a hero.

   • 1982 December 25, Peg Byron, “The 1982 New York Gay Film Festival”, in Gay Community News, volume 10, number 23, page 8:

     Berlin-Harlem showed relentless racism, including from the so-called friends of a black ex-GI in Berlin, without putting its central character in a 'white hat' either.

2. (computing, computer security, slang) A well-meaning hacker who hacks for a good cause or to aid a company, organization, or government without causing harm (for example, to identify security flaws).
3. (slang) A sailor.

• black hat
• gray hat

• white hat (computer security) on Wikipedia.Wikipedia