What zombie uses a ladder to climb over tall plants?

What zombie uses a ladder to climb over tall plants? The Ladder Zombie does. It carries a ladder and places it against defensive plants such as Wall-nut, Tall-nut, or Pumpkin, allowing zombies to climb over the obstacle.

This makes the Ladder Zombie more than a tougher version of a normal zombie. Its main threat is the way it changes the board: once the ladder is positioned, following zombies can bypass a plant that would normally delay or stop them. A Tall-nut therefore cannot be treated as a permanent wall when this enemy appears.

The ladder itself can be removed. Explosive plants can destroy it, while Magnet-shroom can pull it away. Replacing or eliminating the blocking plant also removes the ladder, although doing so may open the lane to other attackers.

The Ladder Zombie is especially memorable because it appears in the roof stages of the original game, where defensive plants are essential for controlling lanes. Pole Vaulting Zombie also crosses obstacles, but it jumps over one plant rather than using a ladder to create a route for other zombies.