Aggregation of network traffic source behavior data across network endpoints may be implemented. Indications of endpoint-specific network traffic directed to different network endpoints may be received. Aggregate traffic source behavior data may be generated across multiple aggregation levels. One or more traffic aggregation nodes may be implemented for each aggregation level to maintain different respective portions of the aggregate traffic source behavior data. Different granularity of the aggregate traffic source behavior data may be maintained at each of the aggregation levels. An indication of traffic source behavior for traffic sources may be provided such that responsive actions, such as traffic control actions, may be performed with regard to the traffic sources.