My favourite enemy? One that doesn't kill me too many times. :D
I would say the rainbow treasure goblins in Diablo 3 :) Also, tiny zerglings in a carbot form of course.
I haven't played many brick breaker games before, so it took some practice to get in the groove but I really like this game. Starts out easy for noobs like me but gives a taste of what's to come in later levels. I especially liked the flaming skulls, they make an otherwise simple game exciting and fun. :) Looking forward to more teasers.