After extensive research into the models I have on hand and can get working, here's how I see the units making up the Assassin class:
1. Bandits (Ancient, avail @ Trapping) - Hand Axe Barbs
2. Marauders (Classical, avail @ Currency) - One of the javelin throwers from the Stone Age Pack (
https://forums.civfanatics.com/resources/civ5-stone-age-pack.23674/)
3. Assassins (Renaissance, avail @ Printing Press) - Assassin art (
https://forums.civfanatics.com/resources/assassin.18578/)
4. Guerrillas (Modern, avail @ Radio) - the "paramilitary commandos" from the Crazy Scotsman's Omnibus mod, which is, I think, based on the UK paratrooper, modified to look more paramilitary-like than professional military
5. BlackOps (Information, avail @ Mobile Tactics) - one of the Modern era Spec Forces mods here ( the one looking most BlackOps like):
https://forums.civfanatics.com/resources/categories/civ5-modern-era-units.134/
Just cannot find any "James Bond" or trench coat type units to use here. Closest I found is the actual "Archaeologist" figure from the game - but I'm not sure I can force any combat animations on the unit. I'll experiment with that in a few days, but I haven't had much luck in the past getting civilians to attack. At best they "freeze" for a few seconds while combat takes place, at worse they crash the game when the attack begins.
Finished the first unit - Bandits. Reskinned the Barb Hand Axe unit, as it's the only one I've found that throws something smaller than a spear. I modified the unit so it is now Team Colored - so it will look like it should for any civ. Was thinking about fabricating a bandana for a mask, to take the place of the beard....
Not sure if you think the Bandit should consist of a single figure in the unit or a group. Original Barb Hand Axe has 10 figures at full strength.
Promotions for the class will probably entail "move after combat", "extra chance of withdrawal", "extra defense", "pillage at no move cost", "no penalty for moving in hills and forests", "ignore zone of control" - with the earlier units having fewer of these and less powerful, and later versions having most of them at higher levels. Will probably change the "yield from kills" from faith to gold. Just makes more sense for this class.
May want a paradrop option for #5 as well - somewhere between a normal paratrooper and Xcom - between 9 & 40 squares, maybe 25?
Also - the icon and flag are temp, place holders. I'll work on those later.