(also grey hat hacker)
Hackers who fall somewhere between black and white hackers. They use their hacking knowledge for their own personal gain, but they don't engage in criminal activities. A gray hat hacker is someone who will look for security loopholes in a company's system and then threaten the company to expose it unless they pay a certain sum of money. So they provide valuable information to companies or the public, but unlike white hat hackers, they use unethical methods to obtain it. Gray hat hackers don't usually work to make money directly. Their aim is often to make a name for themselves, become famous in the cybersecurity community, and advance their personal career.
In 2013, computer security researcher Khalil Shreateh hacked Mark Zuckerberg's Facebook profile. He found a glitch that allowed him to post to anyone's Facebook wall and reported it to Facebook. The company ignored the hacker's report, so Khalil decided to post on Mark Zuckerberg's wall using the loophole that he found. Facebook promptly responded, demanding to know how the hacker found the bug but refusing to pay him the bug bounty.