Top 5 background Deus Ex characters too minor to 1) have custom skins/models 2) reoccur in later levels or 3) have lengthy conversation lines (subject to change because I'm probably going to replay this fucking masterpiece soon after having watched a couple brief gameplay bits on YouTube and realizing how much I've forgotten):
5. The chick with the weird fake southern accent in the Underworld Tavern
4. The "You made a big mistake, home boy" drug dealer
3. The "Yeah, like Nietzsche" UNATCO soldier
2. The canal boat chick that sells you weapon mods
1. The Erin/Decker/Young love triangle*
*NSF commanders mentioned in the first few levels but never seen until you reach their end, indistinguishable in person so I'm lumping them all together