“Threat actor” is the name given to cyber attackers. Threat actors can be individuals, groups, organizations, or even nation states. Sometimes they will attack because there is an opportunity, and sometimes they have very specific, target reasons.
Individual threat actors are often called hackers, and can have very different motivations. “Black hat” hackers have malicious intent – stealing, destroying, and moving through computer systems without the owner’s permission. “White hats,” on the other hand, work with system owners against black hats to protect systems and data from theft, destruction, or even ransom. Of course, there are “gray hats” as well. They act as mercenaries for groups that pay them for their cyber-skills.