Hacktivists are hackers with an ideology, who strongly believe in a cause and are willing to break the law to further that cause.
Hacktivists are defined by their strong motivation; this motivation means that they can be very difficult to dissuade from a target. If one method doesn’t work, they will just try different approaches until something works.
Hacktivists can have a wide variety of objectives that they aim to achieve via hacking. Defacement, denial of service, and leaking confidential information are all common actions taken by hacktivists.
Hacktivists are usually external threats, and they can have a range of sophistication and resources. Their goals are usually in service to whatever cause they are rallying behind. The most dangerous aspect of hacktivist groups is their motivation. Many of these groups have goals that seem noble on paper. For example, revealing corruption or freeing someone being held against their will by an ethically dubious hospital, and it can be easy to see why these hackers would feel strongly enough to take matters into their own hands.