David Keefir is the pseudonym of Keith Silverstein, an established American voice actor known for his extensive work in English dubs of anime series and video games. He was born on December 24, 1970, in Plainfield, New Jersey. The name David Keefir is one of several aliases he has used professionally, which also include David Roach. He is credited as David Keefir for his role as the protagonist Zwei in the 2004 English adaptation of the anime series Phantom - The Animation.

Silverstein's career as a voice actor began around the year 2000. He has since become a prolific figure in the anime dubbing industry, lending his voice to a wide array of characters across numerous popular series. His major roles include the cunning and powerful Hisoka in Hunter x Hunter, the charismatic but deadly Johan Liebert in Monster, and Robert E. O. Speedwagon in JoJo's Bizarre Adventure. He is also known for voicing Mikoto Suoh in the K project, Char Aznable in various Mobile Suit Gundam installments, and En in Dorohedoro.

Beyond anime, Silverstein is a familiar voice in Western animation and video games. He voices Gabriel Agreste / Hawk Moth in the animated series Miraculous: Tales of Ladybug & Cat Noir and Vector the Crocodile in the Sonic the Hedgehog video game series. His extensive video game repertoire also includes portraying Torbjörn in Overwatch, Shen in League of Legends, Zhongli in Genshin Impact, and HUNK in the Resident Evil franchise.

Throughout his career, Silverstein has frequently collaborated with major dubbing studios such as Bang Zoom! Entertainment, Studiopolis, and NYAV Post. He has worked alongside many other prominent voice actors, building a reputation for his versatility in portraying both heroes and villains across a wide spectrum of genres. His performance as Hisoka in Hunter x Hunter, in particular, is frequently highlighted by fans and critics as a standout role that captures the character's unsettling and unpredictable nature.