1. The Halkonans - Mirror, Mirror (The Original Series)
Double the laziness and all in just one episode. These peaceful aliens have some resources that the Federation vitally need and for makeup to emphasise their alien nature we'll stick a blue dot on their foreheads. This might just be the second cheapest makeup job alongside the "Parallel Earth" episodes. What makes this even more impressive is the fact that the Halkans appeared in Mirror Mirror in both of the universes and not only are they still peaceful but they get a makeover and get to look a little bit tired. Stunning. On a second point it's also worth considering that the budget was pretty much minimal for this episode unless that scar on Sulu's face cost a packet which shows just how lazy it was that the only alien featured aside from Spock couldn't even get some plastic enhancements. Apparently they had some surplus blue paint instead and so became a new race in Star Trek - or two if you're counting universes.
Reminds us of: That Saturday morning hangover