A threat actor is any individual, group, or organization that initiates or carries out malicious activities in cyberspace, such as hacking, data theft, or spreading malware. Threat actors can include cybercriminals seeking financial gain, state-sponsored hackers with political motives, hacktivists promoting social or political causes, or even insiders misusing access to sensitive systems. Understanding the types and motivations of threat actors helps organizations develop better cybersecurity defenses and respond effectively to potential attacks.