The seven operational risk loss event groups recommended by the Basel Committee are:

1. Internal Fraud
2. External Fraud
3. Employment Practices & Workplace Safety
4. Clients, Products, & Business Services
5. Damage to Physical Assets
6. Business Disruption & System Failures
7. Execution, Delivery, & Management Process

However there are alternative classifications:

1. Employee: loss events resulting from the actions or inactions of a person who works for a firm.
2. Business Process: loss events arising from a firm’s execution of business operations.
3. Relationships: loss events caused by the connection or contact that a firm has with clients, regulators, or third parties. This category focuses on the interaction between a firm and other entities; relationship risks involve both parties.
4. Technology: loss events due to piracy, theft, failure, breakdown, or other disruption in technology, data or information; this category also includes technology that fails to meet the intended business needs.
5. External: loss events caused by people or entities outside a firm; the firm cannot control their actions.

I'm sure there are more..