Todd

Todd
Common Ground (3×07), The Seer (4×08), Miller’s Crossing (4×09),
Be All My Sins Remember’d (4×11), Spoils of War (4×12), The Kindred, part I (4×18),
The Last Man (4×20), The Queen (5×08), First Contact (5×10), The Lost Tribe (5×11),
Infection (5×17), Vegas (5×19), Enemy At The Gate (5×20) –
Christopher Heyerdahl

Except in Be All My Sins Remember’d – voiced by Heyerdahl but played by Brendan Penny and possibly Spoils Of War because there is conflicting information about who played him in this episode.

Appearance in SGA: Legacy as Guide

Billy

Billy (he was never named on the show but the First Contact end credits refer to him as Billy Wraith) – The Queen (5×08 (probably)), First Contact (5×10) –
James Chutter

Note – Whoever wrote this Stargate wiki entry for Billy regards James Chutter’s Bridge Officer Wraith and Billy as being the same character. The facial hair and forehead tattoo is the same for both so it’s logical that they are supposed to be the same Wraith.

Appearance in the Stargate Atlantis: Legacy novel series as Precision.