End of Turn: Transform another random Zombie into a 5/5 Knight of the Living Dead with Armored 2.
Contrary to popular opinion, it's just OK to be king.
Zombie King is a premiumlegendaryzombiecard in Plants vs. Zombies Heroes, and a member of the Hearty class. He costs 4 to play, and has 2/5. He does not have any traits, and his ability transforms a random zombie into a Knight of the Living Dead at the end of every turn, starting from the turn he is played, excluding him and other Knights of the Living Dead.
Statistics
Class: Hearty
Tribes: Mustache History Zombie
Traits: None
Ability:End of Turn: Transform another random Zombie into a 5/5 Knight of the Living Dead with Armored 2.
Set - Rarity: Premium - Legendary
Card description
Contrary to popular opinion, it's just OK to be king.
Update history
Update 1.16.10
Rarity change: Super-Rare → Legendary
▲ Strength change: 0 → 2
Update 1.22.12
Animation change: Legendary shine has been added
Strategies
With
Zombie King is a brute force to reckon with. He can easily turn the tide of the battle almost instantly. While he has low strength, his ability certainly makes up for it. Using this as early as possible is the optimal use, as getting Knights of the Living Dead early makes a huge difference, since they are very tanky and hit hard.
Another good thing is that Zombie King has 5, which means he can sustain most attacks early in the battle. Using this with cheap fighters is also recommended, as he will turn even the weakest zombie into a very powerful one. However, be careful as the plant hero may stop cheap fighters from turning into Knights of The Living Dead. It is also advisable to bring zombies that could resist attacks like Conehead or Buckethead so they have a higher chance of being affected by his ability.
However, if this is still in play while playing a more powerful card like Octo Zombie, Zombot Plank Walker, or Portal Technician, beware, as the Zombie King can turn those into knights as well, essentially downgrading them.
Allowing this zombie to upgrade Amphibious zombies is an extremely good idea, as there are not many Amphibious plants strong enough to take Knights of the Living Dead out. Guacodile is one of the few plants capable of doing that.
Having two of these out on the field at once may not help, as they can potentially transform each other into Knights of the Living Dead as well, only having the ability to attack.
Considering using Coffee Zombie after this has transformed many zombies into Knights of the Living Dead, as the Coffee Zombie will give each of the Knights of the Living Dead, Zombie King, and himself +1/+1 as well as Frenzy, creating an unstoppable force that will tank extreme amounts of damage, destroy all plants in their path and strike through to the hero.
Try to avoid playing Zombie King himself as the plant hero may easily find a way to destroy him quickly. In that case, play the Zombie King if there are at least 2 zombies on board so he has a chance to turn a random zombie into a Knight of the Living Dead. Against Green Shadow, don't place this in the middle lane unless she has already used Precision Blast.
This zombie also works effectively with Rustbolt and Transformation Station. If Zombie King transforms a zombie that is in said environment, that zombie will transform into an 8-brain cost zombie such as Octo Zombie or Zombot Plank Walker, which is enough to turn the tables.
As of update 1.22.12, Zombie King is much better in a sports deck, as the zombies he transforms into has synergy with Team Mascot and Zombie Coach.
Against
This is a very difficult zombie to confront, despite having low strength and thus, not a threat strength-wise. Because of this, using any plant that has 3 health or more is safe for a turn, unless the zombie hero plays tricks. Bouncing Zombie King is overall a decent option, as he will not transform a zombie on field into a Knight of the Living Dead. Most likely though, he will appear again the next turn. Another strategy is to destroy all the other zombies, as he won't be able to transform anyone.
Plants that do damage to all zombies like Sour Grapes or Kernel Corn are great, as they can whittle down his health. However, the Knights of the Living Dead will survive. To deal with them, using Doom-Shroom will easily take all of them out, at the cost of plants as well. Mirror-Nut can also help, as it can provide easy fodder to knights to attack the zombie hero directly. Bouncing the Knights of the Living Dead he transforms into can also be a good option, since they are quite expensive to replay.
While the player can leave Zombie King on the field to allow stronger zombies to be transformed into weaker Knights of the Living Dead, it could be costly to the player to do so as the Knights of the Living Dead will steamroll through most early-game plants while not taking much damage themselves due to their Armored 2 trait.
If Zombie King is played in the middle lane, Precision Blast is the best way to finish him off, but only when you are playing as Green Shadow. If you are playing as a Kabloom plant hero, Sizzle is also able to destroy him instantly, provided his health does not get boosted. If you are playing as a Solar plant hero, use instant-kill cards such as Squash and Whack-a-Zombie.
Gallery
Plants vs. Zombies Wiki has a gallery for Zombie King (PvZH).
In Plants vs. Zombies 2, he can only transform Peasant Zombies, Conehead Peasants and Buckethead Peasants into knights by giving them knight helms. In this game, however, he can transform nearly anything into Knights of the Living Dead, up to and including Imps, Gargantuars, machinery, animals and even other Zombie Kings.
As Neptuna, if the player gets a Super Block and plays Octo-Pult immediately after getting it with a Zombie King on the field, the Octo-Pet instantly becomes a Knight of the Living Dead when it is played.
Since the Thanksgiving update, it still works, but rarely unless it is the only other zombie on the field.
Zombie King can transform an Amphibious zombie in the aquatic lane into a Knight of the Living Dead. This is possibly an oversight.
His description is a reference to the quotation "It's Good To Be (The) King" from the 1981 movie History of the World, Part 1.
He is the only one of these zombies to not have his name changed.
Coincidentally, they all have 5 health.
He is the only card to transform zombies into zombies that cost more than him.
He is also the only zombie with the ability to transform one another.
The only zombies that cannot be transformed into Knight of the Living Dead by Zombie King are Zombie Yeti and Cosmic Yeti, as they Bounce themselves before Zombie King can activate his ability.
Zombie King is currently bugged: he can transform Knights of the Living Dead into Knights of the Living Dead, even though that is not normally the case.
Strength
Health
Cost
Armored 2.
Armored 2.
Frenzy, creating an unstoppable force that will tank extreme amounts of damage, destroy all plants in their path and strike through to the hero.
Kabloom plant hero, Sizzle is also able to destroy him instantly, provided his health does not get boosted. If you are playing as a 
Solar plant hero, use instant-kill cards such as Squash and Whack-a-Zombie.
Brainy
Crazy
Hearty
Sneaky
