1. A method comprising: accessing interaction data describing one or more interactions between at least one actor of a plurality of actors of an online social network service and one or more content items accessible on the online social network service; identifying, based on the interaction data, a specific content item posted by a particular actor of the plurality of actors and one or more interactions by respective other actors of the plurality of actors with the specific content item; calculating, by a machine including a memory and at least one processor and based on the interaction data, a leadership score associated with the particular actor, the leadership score indicating a propensity of the particular actor to spread information among the plurality of actors of the online social network service; determining a number of actors from the plurality of actors have each disseminated the specific content item within a predetermined time period after the specific content item was uploaded to the online social network service by the particular actor, the number of actors being within a predetermined number range; and classifying, based at least in part on the calculated leadership score, the particular actor as an information propagator among the plurality of actors of the online social network service.