Recomended

Mutant rabbits

Mutant rabbits can spawn in the Taiga biomes and other places. They have 90 health. There's a chance they will jump really high. They are tameable; tame them using carrots. They have 34 damage. They are neutral. They also drop mutant rabbit hide and rabbit meat.

Mutant Chickens

Mutant chickens have two variants, melee and range. They have 100 health. Melee ones deals 12 damage. They are tameable; tame them with seed. They are also rideable. Also, the range ones can deal 1 damage in every egg bullet when it hits you. I'll talk about about the egg bullets, once we are done with the Mutant Mobs. Also, their rivals are mutant foxes. Mutant Chickens spawn mostly everywhere in the overworld. They also drop thick feathers, normal feathers and chicken meat.  

Mutant foxes 

Mutant foxes spawn like mutant chickens almost everywhere in the overworld this thing has 130 health and is also neutral it can deal 15 damage and poison you this is also tameable with meat also rideable but is faster than mutant chicken also there's a chance it can jump on you and will drop mutant fox fur also

Mutant endermite 

Mutant endermites can spawn in the end at night so don't go in the end in nighttime ok, it has 88 health and can deal 23 damage and can weakness effect it, also it will drop powerful enderpearl to craft powerful enderpearl staff, normal enderpearl, the ender eye, and other drops

Mutant strider 

Mutant strider are very hostile to every mob in the game, it has 210 health it will deal 63 damage and will wither effect you also he shouldn't be mountable but he can be ridden and idk how im gonna fix it and it drops mutant strider armor, and will spawn everywhere in the nether

And the final mutant, Mutant golemor 

Mutant golemors are really op so be ready while killing this thing, it has 1000 health it deals 25 damage while withering you they very rare to spawn and if you find it you are lucky, it will drop diamond block, iron block, and the rarest, the golemor dust