Dr. Zomboss

Dr. Edgar George Zomboss is the final boss and the ruler of the zombies in the game, and is battled in level 5-10, the last level of Adventure Mode and of the Roof Stage. In truth, this level is just a sneak peak at the Mini-game Dr. Zomboss's Revenge, where he is also played. The battle with Zomboss is the only night level on the roof, probably so that Coffee Beans won't need to come in order to wake up the Ice-shrooms which can be troublesome.

He sends out other Zombies to attack you -  only Flag Zombies, Dancing Zombies (and Backup Dancers), Digger Zombies, Balloon Zombies, Aquatic Zombies, and Zombie Bobsled Teams (despite ice trails from Zombonis) do not appear. The Zombot also has its own attacks, most importantly fireballs and iceballs which are released from its mouth when it bends down, which is the only time when it can be damaged. The boss battle itself is a Conveyor-Belt Level, so seed packets come on the conveyor belt at the top of the screen. The only seed packets that can appear are those of the Flower Pot, the Cabbage-pult, the Kernel-pult, the Melon-pult, the Jalapeno, and the Ice-shroom. This zombie is really easy to defeat even though he's the game boss.

Health
Estimated Absorption of 20,572 Normal Damage Shots. Multiple appearance changes occur, and an explosion occurs after about 19,371 Normal Damage Shots, before surrendering at 20,572 Shots.

Attacks
Dr. Zomboss has four attacks. When not attacking he sends zombies at you, placing them at the far end of the flat section of the Roof.
 * The most common attack is to duck down so you can see the Zombot's head. After a short delay the Zombot's eyes will glow either red or blue, signaling his attack:
 * If red, he will unleash a fireball. Use an Ice-shroom to extinguish it.
 * If blue, he will unleash a snowball. Use a Jalapeno to melt it (making sure to plant it in the same row).
 * Another attack is to dangle three Bungee Zombies from the Zombot's hand. They will steal three plants if you do not kill them.
 * If the player plants any plants off of the sloped section of the roof, on the flat part, Dr. Zomboss may squash them with the Zombot's foot.
 * Dr. Zomboss will occasionally throw a camper at your plants, instantly crushing everything in a 3 square wide x 2 square tall area.

Strategy

 * Always have an Ice-shroom and Jalapeno ready for the Zombot's snowball and fireball attacks;likewise for the Bungee Zombie attack.
 * If possible, save them up for Dr. Zomboss' attacks and for tougher enemies such as Zombonis and Gargantuars.
 * Never put Melon-pults on the first pot of the lane, and instead plant cabbage-pults there. This will prevent you from losing the Melon-pults to the Catapult Zombie's basketballs.
 * Never keep all your Melon-pults next to each other; doing this helps save plants from the camper thrown by the boss. You will risk losing a last line of defence if this happens.
 * When Dr. Zomboss ducks down to attack you with an snowball or fireball, use Ice-shrooms to freeze him so that your plants have more time to do damage.
 * Avoid using a Jalapeno while he is frozen, as this will un-freeze him and let him move away.
 * It is also possible to keep re-freezing him with multiple Ice-shrooms before and after he attacks, providing a huge opening for your plants. But save at least 2 of them.
 * Butter cannot paralyze the Zombot.
 * Leave a column of empty Flower Pots on the first slanted column of the roof as a buffer zone and to plant Jalapenos and Ice-shrooms in, and keep your plants behind them, but don't plant them farther up the roof or Dr. Zomboss may crush on them.
 * For a quick finish, save a lot of Ice-shrooms and when Dr. Zomboss lowers his head, place a Ice-shroom. Right after he starts moving again, place another Ice-shroom. Keep Doing this and he'll be killed in no time.
 * Dr. Zomboss always places four regular Zombies, four Conehead Zombies, he then lowers down to breath out a snow/fire ball, then he comes back and aces four Buckethead Zombies, lowers down his head again. After that, the Zombies he places are completely random.

Trivia

 * The name Zomboss is a portmanteau of the words "Zombie" and "Boss", meaning "Zombie Boss".
 * Just like the Zombot is the combination of the words "Zombie" and "Robot", meaning "Zombie Robot".
 * On level 5-9, Dr. Zomboss leaves a note in excellent cursive, proper grammar, and correct spelling; but after every other ninth level, the note is scribbled down in horrible handwriting and utilizes horrible grammar and spelling written by the Zombies. This is presumably because unlike zombies Dr. Zomboss is intelligent.
 * Due to this it looks like Dr. Zomboss has a brain, which means there is no reason for him wanting to steal the player's, but in his note it asks the player (or "homeowner" as he refers to you) to hand over their house and brains. Perhaps Dr. Zomboss is only there to help the weak zombies eat the player's brains.
 * Dr. Zomboss has a degree in Thanatology, the study of death and the emotions surrounding it, further showing his intelligence as opposed to other zombies who are stupid.
 * In the Zombies on Your Lawn music video, Dr. Zomboss's Zombot is seen dancing on the roof along with the other zombies.
 * Dr. Zomboss has his own music, which is called Brainiac Maniac.
 * Dr. Zomboss bears a very distinct resemblance to Cryptosporidium 136 from the Destroy All Humans! series, and also the purpose (and behaviour) of collecting brains.
 * Cryptosporidium 136's purpose is to collect Furon DNA from the brain stem, but Dr. Zomboss's is unknown.
 * Another resemblance is their heads, looking like they have enlarged cerebral cortexes.
 * It is very odd how the player's roof can support Dr. Zomboss' gigantic robot, the multiple heavy zombies he has attack the player, and the campers that the Zombot throws without collapsing, even when the roof is full of cracks.
 * It's likely that either the Zombot is made out of a strong, light metal (like aluminum or titanium) or the developers decided to ignore this completely.
 * Dr. Zomboss is not killed when defeated, but instead raises a white flag, indicating that he surrenders.
 * It is unknown where Dr. Zomboss gets the zombies he places from, as there are no zombies shown on the zombie side.
 * It is possible that they are stored inside the Zombot, but this is unlikely as it is full of bundles of wires and motors, as can be seen when the Zombot is destroyed.
 * The level progress bar is changed into Dr. Zomboss's health bar for the levels he is present on.
 * In the X-Box 360 version, the Utility Pole that marks where the zombies appear is removed to allow the player to see more of the roof and the Zombot's details, unlike other Roof stages.