Holt of the Secret Service

Jack Holt / Nick Farrell

Kay Drew

'Lucky' Arnold

Quist

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

Ed Valdin [Chs. 1-10]

Garrity [Chs. 11-15]

Rankin [Chs. 11-15]

Dent [Chs. 11-15]

Chief John W. Malloy (as Montague Shaw)

Agent Jim Layton

Agent Frank [Chs. 3-5, 8-9, 15]

John Severn - Engraver [Chs. 1-4]