Robert McElhenney III is an American actor, writer, producer, podcaster and businessman. He is best known for his role as Ronald "Mac" McDonald on the FX/FXX comedy series It's Always Sunny in Philadelphia, a show he co-created with Charlie Day and Glenn Howerton and on which he continues to serve as an executive producer and writer. He is also known for playing Ian Grimm on the Apple TV+ comedy series Mythic Quest, which he co-created with Day and Megan Ganz as executive producers.