Final answer:
An actor representing someone by speaking their lines and engaging in action is known as impersonation, involving the creation and portrayal of a different persona.
Step-by-step explanation:
When an actor represents someone by speaking their lines and engaging in action, this is referred to as impersonation or playing a character. The process involves the actor creating and bringing to life a persona that is different from their own. As described in the works of Shakespeare and practices like those in Haitian Vodou, the actor uses their own experiences and emotions to authentically portray the character. This act of character portrayal involves not only the mimicry of the character's lines but also their actions, behaviors, and emotions to convincingly inhabit the role.