It's Always Sunny in Philadelphia has no shortage of colorful characters both in the main cast and the guest starts on the series. While there have always been a variety of one-time celebrity guest stars, there are a few reoccurring characters that never fail to bring delight to the fans. It's Always Sunny has managed to create a lively world that revolves not only around the series' leads, but also creates in-depth side characters that help to enrich multiple stories.
Source：https://www.cbr.com/its-always-sunny-gail-artemis-mcpoyle/
