Robert McElhenney III is an American actor, director, producer, and screenwriter. He is known for playing Ronald “Mac” McDonald on the FX/FXX comedy series It’s Always Sunny in Philadelphia (2005–present). He is also one of the developers, executive producers, and the creator of the show, which has provided him with writing and directing credits for various episodes. He is also known for playing Ian Grimm on the Apple TV+ comedy series Mythic Quest (2020–present). He also created the series and serves as a writer and executive producer.