The Mutant Creatures mod contains 21 new monsters along with minions and easter eggs in Minecraft PE.
If you're looking for an add-on to take the game up a few notches, this is a great option.

Mutant creatures

Creeper Zombie & Husk: This is an improved version of the normal zombie Minecraft. They can be stopped by knocking them down, but they will rise and become stronger. They are able to summon minions that last for about a few seconds.

Monster Creeper: A monster with four legs and a crooked neck that makes them look like a spider, but a little scarier. After defeat with low health, just run!

Creeper Skeleton and Tramp: Both of these creatures have become master archers with their special arrow that pierces any mob it comes into contact with.

Dry Mutant Skeleton: This type of Dry Skeleton has never looked as scary as its two Stone Swords.

Monster Piglin and Piglin Brute: This piglin beast with its own crossbow and golden sword is only neutral if the player is dressed in all gold. Giving them gold or a gold block will get you something more, but it takes longer, he instantly attacks with his golden battle axe!

Zombie Minecraft Piglin and Pig: One of the neutral creatures that only attacks if attacked. He walks around the bench and also summons minions. He will deal a lot of damage with his golden sword.

Monster Snow Golem: This is a stronger version of the Snow Golem. As if leaving a trail of snow, this one will turn water into ice!

Iron Golem Monstwer: A powerful golem beast that looks a lot like a warden on mod Minecraft PE. It can take out a few creepers at full power, but will need to be repaired over time after brutal fights. Up to 2 players can ride it.

Endolotl Mutant: A floating ender axolotl-like creature immune to anything related to water.

Сreature Ocelot: A strange beast, a mutated leopard, a lynx and a tiger, with various variants. A mundane one that lives in the jungle, a fancy cave variant that somehow survives in deep caves, and a snow variant that walks very easily on packed snow.

That's not all, the mod for Minecraft PE contains the following monsters:

Bouldering & Lobber Zombie Minecraft
Axolotl
Mutant wolf
Skeleton wolf
Creeper spider pig
The drowned
Zombie Enderman
Egg creeper
Hulk's hammer

Disclaimer:

The Mutant Creatures mod is not an official Minecraft product, not approved or not associated with Mojang.