Pre-gen NPC's

Is there anything anywhere in roll20 5e where i can just drag and drop premade npcs...5th level mage...5 level rogue and so on?

If you mean "NPCs built using PC rules", then not that I am aware of. Such a product would likely need to be limited to SRD races and classes at any rate, unless someone went to a lot of work. This would also make trading such characters difficult on a large scale. It's also not in keeping with the rule system, which simplifies PC classes for NPCs, using NPC statblocks: veteran, thug, apprentice wizard and so forth. The best bet is to use these provided statblocks and customize as need be.