Geoffrey Chalmers is a name used by the experienced American voice actor Michael McConnohie for select roles in anime and video game dubs. With a career spanning several decades, McConnohie has contributed extensively to the field as a voice actor, writer, and director, often working under pseudonyms like Geoffrey Chalmers, Jeffrey Platt, and Jeremy Platt. He is known for his deep, authoritative vocal range, frequently portraying villains, mentors, and narrators.

A specific example of his work under the Geoffrey Chalmers pseudonym is the character Dr. Adams in the 2015 original video animation Cyborg 009 Vs. Devilman. In this crossover, Dr. Adams is a mad scientist from the Black Ghost organization who creates a new line of "High-Teen Number Cyborgs" and seeks to merge a cyborg with a demon. His role as this antagonist was part of the English dub produced for the series. Another role credited to Geoffrey Chalmers is Gennai Ishikawa in the 2013 anime series Coppelion.

Beyond these specific credits, Michael McConnohie's broader body of work includes numerous prominent roles in anime. He is recognized as the voice of the Narrator in Hunter x Hunter and Bobobo-bo Bo-bobo, Charles zi Britannia in Code Geass, D in the Streamline Pictures dub of Vampire Hunter D, and Van Grants in the video game Tales of the Abyss. He has also been a recurring voice in the Sonic the Hedgehog and Mortal Kombat game franchises. In addition to acting, McConnohie has directed English adaptations for series such as Berserk (2016) and Cyborg 009: Call of Justice, and, with his partner Melodee Spevack, runs the production company VoxWorks.