A storm giant escort in wakening lands
 

http://imageshack.com/a/img28/6884/exl8.png

Not sure if this is classic or not, but I'm able to Assassinate storm giant escorts in WL (roughly +864.40, -4219.92).

Only giants so far that I've had it happen on, didn't ever go off on the lower lvl ones in Eastern Wastes.

a storm giant escort Body Type : Humanoid
a frost giant berserker Body Type : Giant

Yes, a storm giant escort should be able to be assassinated and working as intended.

Huh, I didn't think Magelo was around anymore, handy site, thanks.