Ryan O'Flannigan is the professional alias of American voice actor Kerrigan Mahan, recognized for his pioneering work in the English dubbing of Japanese anime during the 1980s and 1990s. Born on January 27, 1955, in Los Angeles, California, Mahan adopted the pseudonym Ryan O'Flannigan for a portion of his voice-over credits, particularly in the early years of his career.

His career began in the entertainment industry with on-screen roles, but he soon transitioned to voice-over work, becoming one of the early figures in the field of anime localization. He was involved in dubbing hundreds of foreign films and Japanese animated series into English, helping to introduce the genre to a wider American audience. He is noted for his vocal versatility, with a range capable of portraying both youthful, exuberant characters and more sinister, sneering villains.

Under the name Ryan O'Flannigan, he provided voices for several notable anime titles. He is credited as the voice of Terence Terry Drake in the English adaptation of the classic series Space Pirate Captain Harlock, a role that connected him to the enduring Leiji Matsumoto universe. He also voiced Lord Peter Kensington in the original video animation Fairy Princess Minky Momo: La ronde in my dream. Additionally, his work under this alias includes voicing the character Zedaki, known as Yamcha, in the Harmony Gold English dub of the Dragon Ball movies Curse of the Blood Rubies and Mystical Adventure.

Beyond his credits as Ryan O'Flannigan, his broader body of work as Kerrigan Mahan is extensive and includes some of the most iconic roles in Western animation and live-action television. He is widely known as the original voice of Goldar in the long-running series Mighty Morphin Power Rangers and its sequel Power Rangers Zeo. His other prominent roles include Jeb the talking dog in VR Troopers and the original Magna Defender in Power Rangers Lost Galaxy. In the anime realm, his voice can be heard in classic titles such as Robotech, Vampire Hunter D, and Lensman. His work also extended to video games, with roles in titles like Star Trek: 25th Anniversary and Lighthouse: The Dark Being. Throughout his career, Mahan has also worked as a voice director on various projects, including English adaptations of Grimm's Fairy Tale Classics.