Daniel Riordan is an American actor with a prolific career in voice-over for animation and video games, complemented by numerous on-screen television and film appearances. His professional acting career began in the mid-1980s, with early roles including a part in the film Breakin' 2: Electric Boogaloo and guest appearances on television series such as Star Trek: The Next Generation. Throughout the 1990s, he continued to build his resume with roles in popular shows like The Fresh Prince of Bel-Air and the film Jingle All the Way, where he portrayed the iconic Turbo Man.

Riordan is perhaps best known to animation fans for his work in the 2000 English dub of the Japanese anime series Transformers: Robots in Disguise. In this series, he voiced multiple key characters, including the primary antagonists Megatron and his upgraded form, Galvatron. Additionally, he provided the voice for the combined Autobot warrior Omega Prime. This performance placed him within the legacy of actors who have voiced the iconic Megatron character in the Transformers franchise. His other animation voice credits include roles in Avatar: The Last Airbender as General Mung and The Wild Thornberrys.

A significant portion of Riordan's career has been dedicated to voice work in video games, where he has portrayed a wide array of characters. Some of his most notable and critically acclaimed roles include voicing Alduin, the primary antagonist in The Elder Scrolls V: Skyrim, and Bhunivelze in Lightning Returns: Final Fantasy XIII. His extensive video game filmography also features performances as Primarch Adrien Victus in Mass Effect 3, Colonel Matthew Garret in Days Gone, Cabot in Evolve, and Martian Manhunter in Justice League Heroes, among many others. His work demonstrates frequent collaborations with major game developers and a consistent presence in high-profile releases across two decades.