A captain of the Dark People's Shadow Ships. This title is only revealed in Dreamfall.
During the story, a Shadow Ship is docked in Marcuria's Shady Quay, with the Shadowguide keeping watch. His behaviour is quite odd, and he initially refuses April passage to their ship. When she argues that she has sailed on one in the past and brings up her status as a Wave, the Shadowguide replies that, even if she was one in the past, she is not now. He also says he knows of "no such creature" as the White Kin. Remembering their bibliophilia, April is able to barter passage to the Dark People's City with the only surviving copy of Roper Klacks' memoir - Farewell to My Wizardin' Days.
The Shadowguide's lack of recognition is even stranger given that April, upon arrival in their city, is recognised by another Dark Person as a Wave. It seems impossible that the Shadowguide is cut-off from the Dark People's hive mind, because he uses it to discover whether or not they have a copy of Klacks' memoir. This has lead to speculation that he lies to April when he does not recognise her as a Wave, and suggests that such a sinister character might be the mysterious assailant of the White Kin.
The Dark Person who meets April, puzzled by the Shadowguide's behaviour, suggests that perhaps "he was confused, or his eyes were clouded" (assuming Dark People have eyes). It is possible, therefore, that there is some kind of interference in Arcadia, similar to Stark's Static. This might help explain the White's failure to 'feel' her siblings, and even April's inability to Shift (although the latter seems unlikely to be connected, given that it has ailed her for nigh on 10 years).