Failed Experiment

Failed Experiments are large, humanoid enemies found in many biomes once 4 or more Boss Stem Cells are activated.

Behavior

Punches in 3-hit combo, with a final slam attack where it smashes the ground. The Failed Experiment can change the direction it's facing after performing the three quick punches.
Will leap towards the Beheaded when not in melee range. Failed Experiments can't leap to another platform. Instead, they stop when they encounter an edge, as the case with the Zombie.
The first attempt to damage it will end with the Failed Experiment dashing behind the Beheaded. It cannot perform another dodge until 15 seconds elapse. Note that it will still dodge if the first attempt to damage it is with a parry using a shield.

Elite Failed Experiments have no attack pattern changes, but their leap is a lot faster, and they are harder to stun, as with any other elite.

Punch and Slam

Leap

Description: Performs a leap in the direction of the player. This attack only occurs at long range.
Can be blocked, parried, and dodge rolled.

Both of its attacks can be dodged by rolling as well as parrying. This also goes for the head slam at the end of its regular combo which can be parried. However, it can dodge parries if it is the first “attack” directed at it, so it may be better to hit it with something else first so that you can parry it without interruption.
With heavy weapons and other typically slow weapons, their dodge can be baited out while the player is still charging the attack, allowing for the weapon to be flipped around and successfully hit the Failed Experiment.

The Failed Experiment enemy is a likely product of The Alchemist's experiments, hence the name.
They take the place of the Zombie on higher difficulties.

Failed Experiments were added with the v1.2 update, aka Rise of the Giant DLC in March 2019.
Their design, mainly their drill hand, may be inspired by the Bouncer Big Daddies from Bioshock, which have a similar armament.