Spawn Egg

A spawn egg is an item used to spawn mobs directly.

Obtaining
Spawn eggs can only be obtained in Creative mode, or by commands. In Creative mode, the player can press on an existing mob to obtain their respective egg. Spawn eggs are also available in the Creative inventory. There are 43 eggs available in all editions (51 in Java Edition and 50 in Bedrock Edition).

Commands
Spawn eggs can be obtained by using. See here for all available spawn eggs and commands.

Any spawn eggs not listed in the table below cannot spawn entities. They will instead make a sound as though an arrow has been shot. These eggs will be the default color, white with gray spots. When a player hovers over the image with their mouse the name of the egg is "Spawn ". This egg has no specific properties and can not spawn any mob, except for Bedrock Edition in which some "hidden" spawn eggs obtained from commands that spawn other entities like primed TNT and wither skulls.

Usage
A spawn egg is used by pressing on any surface (top, bottom or side) with the egg. When used on a top surface, the egg's mob will appear with its feet immediately adjacent to the surface.

Spawn eggs are not thrown (unlike normal eggs); the player must be within normal range of the block to use the spawn egg. Hostile and neutral mobs (except wolves, polar bears and llamas) spawned while on Peaceful difficulty will be created, but then instantly deleted from the world.

Dispensers
A spawn egg fired from a dispenser will spawn the mob directly in front of the dispenser.

Baby mobs
If a passive mob has a baby form, and the player its spawn egg on an adult, it will spawn a baby version of that mob, rather than an adult. Other mobs such as evokers, vindicators, vexes and zombie pigmen don’t breed.

Monster spawners
Any spawn egg can also be on a monster spawner to change the mob the spawner spawns.

Renaming
Spawn eggs can be renamed on an anvil, and when used will spawn mobs with that name appearing over their head. Their names can only be seen if they are aimed at from four or fewer blocks away. This name will also appear in death messages from the mob killing a player. If you rename a spawn egg by the names described below, the mob will appear described below. If you name a rabbit spawn egg "Toast", the secret skin of the rabbit appears when the egg is used. When a spawn egg is named Dinnerbone or Grumm, it will cause the mob to appear upside down and show the given name above it.

In-Game Description
In most versions, spawn eggs are described as, "Spawns a mob of the type indicated."

Java Edition
The data value of a spawn egg has no effect; instead, the  data tag is used. For example, would cause the spawn egg to create creepers.

If, for the entity tag 'id', a SaveGame ID is used for a mob or other entity that is not listed in the table above, such as  (iron golem), the result would be a spawn egg with the expected name ("Spawn Iron Golem"), but will be the default color (white with grey spots). These eggs cannot be used to spawn mobs directly, but can be used to program a mob spawner.

Bedrock Edition
When using the command to give a spawn egg, it requires the numeric ID of an entity; for example:  would give an egg that spawns a creeper. For reference, see Bedrock Edition data values for a complete list of entity IDs.

Eggs can be given not just for mobs listed in the table above, but for a few other entities. These eggs will be uncolored (white with grey spots), and will be called by unlocalized placeholder names, or simply, "Spawn".
 * The snow golem (21), iron golem (20) and item (64) spawn eggs can be given, but will spawn nothing.
 * The ender crystal spawn egg (71) produces an end crystal.
 * The boat (90) egg will place a boat on the ground.
 * Using any other entity ID will fail to give the egg.

Trivia

 * Data values differ between platforms. However, the ID is the same.