Holt of the Secret Service

Jack Holt

Jack Holt / Nick Farrell

Evelyn Brent

Kay Drew

John Ward

'Lucky' Arnold

Ted Adams

Quist

Joe McGuinn

'Crimp' Evans [Chs. 1, 4-15]

Tristram Coffin

Ed Valdin [Chs. 1-10]

Stanley Blystone

Garrity [Chs. 11-15]

George Chesebro

Rankin [Chs. 11-15]