Doppel Platform is a social engineering defense platform that uses AI and threat intelligence to detect and disrupt impersonation attacks across multiple channels. The platform monitors domains, social media profiles, advertisements, messaging apps, email, app stores, and dark web signals to identify threats. The core technology is the Threat Graph, which connects spoofed domains, fake profiles, scam ads, and malicious messaging into unified attacker campaigns rather than treating them as isolated incidents. This graph-driven approach maps how malicious infrastructure is reused and scaled across channels. The platform combines AI agents with human expert oversight for threat validation and automated takedowns. LLM agents are trained on expert decisions to triage alerts and execute responses. The system processes over 100 million signals daily and achieves median phishing domain takedown times under one hour. Doppel Platform includes brand protection capabilities to defend against domain spoofing and fraudulent content, executive protection to safeguard leadership from targeted attacks, and phishing simulation derived from real attacker campaigns mapped via the Threat Graph. The platform also offers security awareness training. The system integrates with existing security infrastructure including SIEM platforms and scales without requiring infrastructure upgrades. It uses collective defense principles where threat intelligence from one detection improves protection across all users.