Nightingale Sentinel

On the map

Race: Imperial
Sex: Male
Class: Thief
Level: 15
Can die?: No: essential
Added by: Skyrim

Where they are

Twilight SepulcherOn the map

Quests they're part of

Darkness Returns

Console

prid 0001A2D2

Picks them out where they stand. Then moveto player brings them to you.

From base GTS 118's own records: the winning copy of Gallus (Skyrim.esm). Where: where the game places them as a game starts; people walk about, so they are not always there.