Enemies World They First Appeared In Description
Amp World 3 An electric enemy. Can be destroyed with a Blue Shell, Mega Mushroom, or Star.
Baby Blooper World 3 Baby versions of Bloopers always found swimming with a Blooper Nanny.
Ball 'n' Chain World 7 Spiked Ball attached to a chain on a block. It spins around and is indestructible.
Balloon Boo World 4 Approaches Mario if his back is turned. When looked at, it stops to inhale oxygen to grow. Shrinks to the normal size of a Boo when it attacks. A Starman, Blue Shell or Mega Mushroom can defeat Balloon Boos.
Banzai Bill World 7 An enormous Bullet Bill. The player can jump on a Banzai Bill to defeat it, just like Bullet Bills.
Blockhopper World 2 Imitates 1-3 Brick Blocks and a ? Block, stacked on each other. When Mario approaches, it comes to life and hops around. Easily distinguished by the fact that the ? doesn't move. Mario can defeat it by ground pounding all the blocks down to the ? Block.
Blooper World 3 Swims in an irregular manner. Can be defeated by fireballs or invincibility.
Blooper Nanny World 3 Swims in an irregular manner, as Baby Bloopers swim after it. Can be beat with a fireballor invincibility.
Bob-omb World 4 Legged bombs with eyes. Stomp on a Bob-omb makes it explode after a certain time.
Boomerang Bro. World 2 A Hammer Bro. that throws boomerangs. Stomp, fireball or invincibility defeats it.
Boo World 3 Facing it will stop it. Looking away from it will cause it to pursue Mario. It is vulnerable to Starmen and Blue Shells.
Broozer World 5 Boxing ghoul-like monster. Can break Brick Blocks and other blocks normally indestructible. Mario can defeat it by jumping on it three times, or hitting him with a few fireballs.
Bullet Bill World 2 It's launched by Bill Blasters. The player must stomp on it to defeat it.
Buzzy Beetle World 5 Just like the Koopa Troopa, stomp it and it'll retreat into his shell. One difference is that it's not affected by Fireballs.
Chain Chomp World 6 It attacks the player by moving its head. The player must ground pound the post it's tied to three times.
Cheep-Cheep World 1 Just a swimming fish. It sometimes hops on land. On land it is defeated with a stomp, but underwater it must be hit with a fireball.
Cheep-Chomp World 3 A big, purple Cheep-Cheep. Approaches Mario to chow him down. Very similar to Boss Bass.
Crowber World 8 Swoops at high speeds at Mario. It is defeated with a stomp.
Deep-Cheep World 6 A green Cheep-Cheep that follows Mario. Use a fireball to defeat it.
Dry Bones World 1 One stomp, and it falls apart. It can reassemble, however. Invincible to Fireballs.
Fire Bro. World 8 Hammer Bros. that spit Fireballs. A fireball or stomp will defeat it.
Fire Chomp World 7 Spits a fireball that follows Mario, causing its tail, made of fireballs, to decrease in length. It self-destructs when it does not have any fireballs left, which can hurt Mario.
Fire Snake World 2 Podoboo with a tail of flames.
Goomba World 1 Brown mushroom-like creature with feet. Defeat it with a stomp or a fireball, shell, mini stomp, etc.
Hammer Bro. World 2 Koopa with headgear that throws hammers. It can be defeated by a stomp or fireball.
Kab-omb World 8 A Bob-omb that lights and explodes when touched by Raining Debris or one of Mario's fireballs.
Koopa Troopa World 1 A form of Koopa with shoes. By stomping on it, it'll retreat into its shell. The shell can slide when kicked, and can also be used to defeat enemies or destroy bricks. It can even be picked up. However, it can hurt Mario when sliding, and a Koopa Troopa can come back out of its shell. If enough enemies are killed by a sliding Koopa Shell, 1-UPs are earned.
Lakitu World 2 Throws Spiny Eggs and has his own cloud. One stomp and it's defeated, and the cloud disappears. If defeated with a shell or fireball, the cloud stays, so Mario can take to the skies in it for a while.
Mega Cheep-Cheep World 3 A big Cheep-Cheep. Defeated by a fireball.
Mega Deep-Cheep World 6 A big Deep-Cheep. Defeated by a fireball.
Mega Unagi World 4 A bigger Unagi. Cannot be defeated, but can be gone through with a Mega Mushroom or Star.
Micro Goomba World 3 This small Goomba works the same as its bigger cousins. Only appears in Mini Pipes, and is the only enemy Mini Mario can kill with one stomp. Other versions of Mario kill it by just touching it.
Moneybags World 5 A hopping pest that at first looks like a coin. Stomp on it or hit it with a Fire Ball to get coins, and if it is jumped on or hit enough times, the player will get a 1-Up Mushroom.
Paragoomba World 2 This Goomba has wings. One stomp makes it lose its wings, and turns it into a Goomba. It can also be defeated with a fireball.
Paratroopa World 1 This Koopa Troopa has wings. One stomp makes it lose its wings, and turns it into a Koopa Troopa. It can also be defeated by a fireball.
Piranha Plant World 1 This plant comes out of pipes, but is also found on the ground trying to bite the player. Throw fireballs or avoid it.
Podoboo World 1 Flames with eyes. Most jump out of lava.
Pokey World 2 A cactus with a flower and face. Its segments will grow back when destroyed with fireballs; hit its face.
Raining Debris World 8 Lava shot from a volcano. Can be defeated with a Starman or Mega Mushroom.
Scuttle Bug World 4 This spider will appear from upwards via its web. One stomp or fireball will drop it off its string and defeat it. Also, some can detach from their strings and walk along the ground.
Skeeter World 3 This bug skates on water and deploys bombs. One stomp or fireball defeats it, and its bombs can be obliterated with fireballs.
Sledge Bro. World 8 An overweight Hammer Bro. that carries sledgehammers. It can be defeated with a stomp.
Snailicorn World 5 Creature with a snail's shell, a horn, and feet. Invincible to stomps, but can be pushed off cliffs.
Snow Spike World 5 The normal Spike doesn't appear, but this one does. Instead of Spike Balls, it throws Snowballs. Defeated by a stomp or fireballs.
Spike Bass World 2 A brown giant fish, with spikes all over. It can be defeated with a fireball, a Koopa Shell, a Starman, and a Mega Mushroom, but returns after a few seconds.
Spike Top World 5 Buzzy Beetles with spikes on their shells which walk on walls. Hitting the block they're on will defeat them.
Spiny World 2 These hatch from Spiny Eggs. Any stomp, even the Ground Pound, will hurt Mario. When they touch water, they turn into Spiny Eggs, only to return to their original form, once the water recedes. Also found on ceilings, and comes down when Mario passes. A good way to kill the ceiling versions is that they are usually found in pairs, and can easily collide with each other. Fireball will also defeat them.
Splunkin World 3 Walking jack-o-lantern enemies. One stomp will cause it to become angry and speed up; a second stomp will destroy it. A fireball will also defeat it.
Squiggler World 7 A tiny Wiggler that comes out of Pipes, and will crawl on walls. A stomp on the head defeats it, but only a ground pound gives up points.
Super Dry Bones World 1 (starts being enemy in World 5) A big Dry Bones. Requires a Ground Pound to cause it to fall apart.
Super Piranha Plant World 2 A big Piranha Plant. Will require 3 fireballs to defeat, but will give up a whopping eight Coins if killed with fireballs.
Super Thwomp World 4 A big Thwomp. The only other difference is that Super Thwomp can crush through bricks.
Sushi World 1 Long sharks that are defeated by fireballs.
Swooper World 2 This bat hangs on ceilings. Flies at Mario when he approaches. Fireballs or a stomp will defeat it.
Thwomp World 4 Tries to crush Mario when he gets close. A shell can kill it, or you can ground pound it while it's on the ground.
Unagi World 4 An eel that lives in gaps, and tries to bite Mario. Invincible to all attacks. Occasionally, they can be found swimming back and forth. These ones can be defeated with a Mega Mushroom or Star.
Venus Fire Trap World 2 A Piranha Plant that spits fireballs. Defeated with fireballs.
Whomp World 3 Jumps and falls to the ground when Mario comes close. Before it gets up, players should execute a Ground Pound on it.

*This enemy appears in only one level