Alastair Duncan is a Scottish actor who has built an extensive career in television, film, and theatre, but is perhaps most widely recognized for his prolific work as a voice actor in video games and animated series. Born in Edinburgh, Scotland, in 1958, he began his on-screen career in the mid-1980s, often credited under the name Neil Duncan. His early breakout role was as DS Peter Livingstone in the long-running Scottish detective series Taggart. After relocating to the United States in the mid-1990s, he continued to appear in live-action television, with guest roles in popular shows such as Buffy the Vampire Slayer, Charmed, Angel, Mad Men, and Westworld.

From the early 2000s, Duncan transitioned significantly into voice acting, becoming a familiar presence in the world of video games. His role as the voice of Mitsunari Ishida in the 2006 game Onimusha: Dawn of Dreams is a notable example of his work in a Japanese video game franchise with a strong anime aesthetic. This performance is part of a vast and varied portfolio of voice roles in major gaming franchises.

Duncan's video game credits are extensive and include several critically acclaimed and commercially successful titles. He is known for his portrayals of Senator Armstrong in Metal Gear Rising: Revengeance, the elven spirit Celebrimbor in Middle-earth: Shadow of Mordor and its sequel, and the wise Norse god Mimir in God of War (2018) and God of War Ragnarök. His work in the Mass Effect series is also well-known, where he voiced the turian Councilor Sparatus and the spectre Nihlus Kryik. Other significant game credits include roles in the Legacy of Kain series, the Tomb Raider series, and Infinity Blade.

In addition to video games, Duncan has had a substantial career voicing characters in Western animated television series and films. His most enduring role in this area is as Alfred Pennyworth, the butler to Bruce Wayne, which he voiced for over fifty episodes of The Batman (2004-2008) and in several subsequent animated films like Batman: The Long Halloween. He has also been a recurring voice in the Marvel animation world, portraying Adrian Toomes, also known as the Vulture, in series such as Marvel's Spider-Man and Avengers Assemble. While his career is rooted in acting for both live-action and animation, his body of voice work, particularly in video games and anime-influenced titles like Onimusha, represents a significant and highly recognizable part of his professional achievements.