I'm pretty sure that there are hero and monster tokens in the base games and maybe also the other worlds have them (i can't remember). The enemy packs didn't have any tokens thou.
As far as i remember there were some yellowish tokens with monster pictures on it. Maybe i'm wrong.
edit: It seems the enemy tokens came with the other worlds.
You are correct.
The core games do not have tokens to represent the enemies but the randomize tokens for heroes can be used for this. In most of the expansions, not the early once, you get tokens for the monsters as well as models (great for traveling).