Villagers don't get scared of giants, and won't spawn an iron golem in defence.

How to reproduce:

1. Get some villagers (at least three, by spawneggs, commands or in the wild)
2. Summon a Giant with the command: /summon minecraft:giant ~ ~ ~ {Invulnerable:true} (this step of course near the villagers.
3. Note that the villagers will still refresh their trades and won't run away.