The Angry Zombie is a new enemy in Thaumcraft. It is a zombie that has red, bulgy eyes and is faster than regular zombies, as well as having much better path-finding skills.
Giant Angry Zombies
Giant Angry Zombies will only spawn in high levels of flux. They are just like normal angry zombies except they could grow up to 5 blocks tall, reach far and hit hard. Their appearance is preceded with the message: A nearby node spews forth something foul. They're often the product of throwing Rotten Flesh or Brains in a Crucible to make Magic Tallow.
Giant Angry Zombies grow in size with each strike, up to about twice the height of a normal zombie; however, since they act like regular zombies and try to follow the player, leading them into areas too small for them helps in causing them damage. They drop normal zombie brains and experience.
When the flux levels are at the level: Dangerous! Giant Angry Zombies appear to still not spawn (at any difficulty) except when using large amounts of rotten flesh in the crucible, 32 pieces seem to be enough to spawn one (not confirmed)
Here's a video that explains the differences between a normal Zombie and a Angry one: