Theo Devaney is an English actor who began his career in live-action television and film before expanding into voice acting for animation and video games. He was born in London on August 25, 1984, and is a graduate of the Oxford School of Drama, where he completed a three-year professional acting training program in 2005. His early on-screen work includes guest roles in television series such as Doctors and Psych, but he became more widely recognized for his recurring role as Gavin MacLeod in the long-running American series Supernatural from 2014 to 2017, and for playing Simon in the A Christmas Prince film series.

Devaney made his debut in anime voice acting with the English dub of the series Moriarty the Patriot, which was produced by Funimation and began streaming in 2021. In this adaptation of the manga based on Arthur Conan Doyle's characters, he provides the voice for the iconic role of Sherlock Holmes. The casting was part of an English dub that notably included several British actors to voice the London-based characters, with Devaney's natural accent lending authenticity to the role. An anecdote from the production notes that the American voice director initially attempted to correct his pronunciation, only to rescind the direction upon realizing Devaney was a native English speaker from London.

His work on Moriarty the Patriot led to a noted collaboration with fellow voice actor Ryan Colt Levy, who played Dr. John H. Watson. Despite recording their lines remotely during the pandemic, the two reportedly developed a close friendship, making a point to have dinner together regularly.

Beyond this anime role, Devaney's voice work encompasses other projects. He voiced the character Aryan La Valette in the video game The Witcher 2: Assassins of Kings in 2011. He has also provided voices for other video games, including Battlefleet Gothic: Armada and Smite. In 2022, he voiced the character Zōffy in the English dub of the live-action Japanese film Shin Ultraman.