Ladder Zombie

The Ladder Zombie, similar to the Screen Door Zombie, carries a shield in the form of a ladder (hence the name). It moves quickly and uses a ladder to get over the first defensive plant (Wall-nut, Tall-nut, or Pumpkin) it encounters and leaves it there so other zombies can climb over it, then continues at normal speed to eat the remaining plants. The Ladder Zombie can eat other plants, even if it encounters them before placing the ladder. For example, if you have a Sunflower in front of a Tall-nut (which would be a bad idea), it would eat the Sunflower, place the ladder on top of the Tall-nut, climb over the Tall-nut, and keep going. It is similar to a Pole Vaulting Zombie, but eats faster, only uses the ladder on defensive plants, can go over Tall-nuts, has more health, and allows other zombies to climb over defensive plants. It is the 21st Zombie you will encounter in Adventure Mode and can be first seen on the Roof.

Suburban Almanac Entry
 Ladder Zombie 

Ladder Zombie climbs over obstacles.

Toughness: medium

Ladder Toughness: medium

Speed: fast, then slow (after placing ladder)

Weakness: fume-shroom and magnet-shroom

He picked the ladder up for $8.99.

Overview
Absorbs 42 normal damage shots. Appearance changes upon 9, 17, 25 (at this point, his ladder is destroyed), and 34 before dying at 42 normal damage shots.

Strategy
Ladder Zombies can be annoying, because they can easily get over your defense, also letting other zombies to do so too. However, there are various way to deal with this zombie. The ladder can be taken away by a Magnet-shroom, even if the ladder was already placed beforehand. Explosive plants, (Cherry Bombs, Jalapenos, Doom-shrooms, and Cob Cannon cobs) will also destroy the ladders after they are placed. These zombies are also weak to Fume-shrooms, Gloom-shrooms, Spikeweed/Spikerock and lobbed-shot plants, (the lattermost of which should compose the majority of your offense in the Roof levels in which the Ladder Zombie appears) as they do direct damage, and do not have to destroy the ladder first. The ladder can also prove to be a weakness to the Ladder Zombie, as Split Peas, Starfruits, and Gloom-shrooms can shoot backwards to damage it directly, making it a good idea to plant them in Pumpkins. This would effectively make the plant invulnerable, until an explosive plant, Magnet-shroom or Blover is utilized; so you shouldn't use both of these techniques at once (or near each other). Of course, this would not be helpful against Gargantuars or Zombonis. Ladders are best for a Chomper inside a Pumpkin, since the Chomper will be left uneaten by Zombies, while they still can eat the Zombies, (not including the one planted furthest to the left). This works especially well if the Chomper is planted on the right side of the lawn.

I, Zombie
Ladder Zombies cost 150 sun. You should use Ladder Zombies to climb over Wall-nuts or Tall-nuts instead of sending plenty of zombies to get over the defensive plants. However, don't use them near Magnet-shrooms, as they will remove the ladder. If there are no defensive plants in a row, they can be a usable substitute for the Screen Door Zombie, with a shield to protect against the freezing effects of Snow Peas, and faster movement and chewing speeds to compensate for the lower health. Avoid rows with Kernel-pults, as they will die quickly from direct contact.

Trivia

 * The Ladder Zombie is the only zombie that has a shield used for more than protection.
 * The ladder is a shield against head-on projectiles. It provides no protection against fume attacks, arcing catapult projectiles, attacks from below (such as those from Spikeweed and Spikerock) and explosives.
 * The Ladder Zombie is the only shield zombie that loses his arm while he still has his shield.
 * The Ladder Zombie only puts its ladder down when it reaches a Wall-nut, Tall-nut, or Pumpkin, but not when reaching a Garlic.
 * If a Ladder Zombie dies just as it is placing its ladder, the ladder will disappear after 2-3 seconds.
 * The Ladder Zombie will not eat defensive wall plants when his ladder is intact.
 * A ladder will disable but not destroy one defensive wall plant. Most zombies approaching from the right side of the screen will climb over it. A Digger Zombie approaching from the left will still attack a defensive plant with a ladder attached.Black_ladder.PNG
 * Unlike the Newspaper Zombie and the Screen Door Zombie, the ladder protects hypnotized Ladder Zombies.
 * The Newspaper Zombie, Jack-in-the-Box Zombie and Ladder Zombie eat without using their hands.
 * The Ladder Zombie actually eats further away from plants than other zombies. This also occurs with Newspaper Zombies.
 * In the DS Version, even if the ladder is damaged, while the Ladder Zombie is eating, it appears to be undamaged.
 * A placed Ladder can be destroyed by an explosive (Cherry Bombs, Jalapenos, Doom-shrooms, and Cob Cannons, and Potato Mines). It can be destroyed by digging up the plant that it is placed on. Placing a Magnet-shroom within range will remove ladders, even if they've already been deployed.
 * If you kill a Ladder Zombie in the progress of placing a ladder, its head will fall off, stop, and fall. The ladder will also disappear.
 * Even if the ladder has taken damage, the ladder will look undamaged when placed on a Wall-nut, Tall-nut, or Pumpkin.
 * The Ladder Zombie, the Imp (while flying), the Balloon Zombie (while on its balloon), the Digger Zombie (while digging), the Gargantuar, the Zomboni, and the Catapult Zombie are the only zombies that can get past a Tall-nut by itself without eating the plant.
 * Even if the Ladder Zombie's ladder is undamaged, it will change appearance to look damaged if the zombie dies while carrying it. The same thing happens with the Screen Door Zombie.
 * The Ladder Zombie has a pencil stuck in the side of his head, a tool belt with a hammer, and a plaid workman's shirt. He was likely a carpenter.
 * The pencil in his head may also explain how the Ladder Zombie died.
 * The Ladder Zombie has the same speed as the Pogo Zombie while holding his ladder. If he loses his ladder (deployed, magnet, broken), he slows down to the speed of a normal zombie.
 * There is a glitch that when a Magnet-shroom behind a Tall-nut or in a Pumpkin steals the ladder, the zombies can still climb over the Pumpkin or Tall-nut, as if the ladder was deployed.
 * There is a glitch in that if a Ladder Zombie loses its arm, the arm will not come off and you can see a bone sticking out of its knee.
 * When an Ice-shroom is activated or a plant is upgraded inside a Pumpkin with a ladder, it is destroyed.
 * Another cause of disappearing ladders against Pumpkins is removing the plant inside the Pumpkin.
 * Ladders are sometimes used in strategies in Survival: Endless to make plants invunerable to eating zombies.
 * The Ladder Zombie, Zombotany Zombies, Dancing Zombie, and Jack-in-the-box Zombie are the only zombies that use their abilities when hypnotized.
 * It is a glitch that sometimes Ladder Zombie's arm wouldn't fall off, however the bone still showed. This gave the appearance of the bone sticking out of the arm.