Ghasts are hostile, Nether dwelling Mobs that float around and shoot explosive fireballs at players. Ghasts are cube shaped with 9 large tentacles hanging beneath them, and their main body is an exact 4×4×4 block cube, but despite their ghost-like appearance and their ability to move through other mobs, they cannot move through solid blocks, and they do not take extra damage from the smite enchantment. Ghasts were first added in the Halloween update and will spawn anywhere in the Nether where there is a 5×5×5 block space.
When a ghast finds a player, it will keep floating around, but it will face a player and start opening its red mouth and eyes and spitting Fire Charges whenever it has a clear shot. The only warning a player will get is the ghast's high-pitched scream before the shot is fired. These fireballs create explosions and light nearby blocks on fire. Due to this, ghasts can very quickly cover the landscape with fire. Ghasts will always float around randomly unless a player comes within one chunk from one, which is when it will attempt to gain altitude but keeps shooting at a player. When wandering, ghasts will make peaceful, medium-pitched sounds, but when fighting, its sounds will sound more like high-pitched screeching. 
Defeating a Ghast
In order to defeat a ghast, if it can be approached, it is best to stay behind walls as much as possible until the distance is close, when it will fly upwards, which is the easiest time to defeat a ghast with a ranged weapon like a Bow. If a player cannot get within range to get the ghast to fly upwards, then it is probably best to defeat it by knocking its fire charges back at it by left clicking while holding any item, which will not always hit, but is effective at defending and attacking at the same time. Alternatively, if multiple ghasts are around, then it is best to try and get one of the ghasts between a player and the other ghast, and allow them to fight each other. Another tactic with a lone ghast is to use a fishing rod to draw it close enough to damage it with a sword.
- Ghasts' hit-boxes are off. Their tentacles "no-clip", which means that the head needs to be attacked in order to defeat it.
- Ghasts cannot destroy Iron Bars or Cobblestone.
- Ghasts will cancel their fire charge if a player that they are attacking moves behind a block.
- Ghasts always look and sound the same, no matter how bright it is, or where they are in relation to a player.
- If the crosshair is moved on top of a ghast's fire charge, then the box around the equipped item will light up.
- Ghasts, if spawned in The End, will automatically be hostile towards the Ender Dragon.
- In snapshots between 1.4.7 and 1.5, the fireball's texture was accidentally changed to a diamond helmet and back again.
- The ghast's sounds are C418's cat. It's apparently pretty much the sound it makes when disturbed while sleeping, or a modification on the cat's sounds.
- The ghast is the biggest natural mob by volume, same with the ender dragon.
- There is a currently unused sound for ghast called "affectionate_scream.ogg".
- A ghast can destroy a portal by extinguishing it, potentially leaving no exit from the Nether. However, if they shoot the disabled portal again, it will relight the portal. However, both of these occurrences are quite rare without player intervention.
- When the ghasts were going to be added in Minecraft, they were planned to be spawned in the Overworld through the Nether portal a player created. This idea was removed.
- However, If the portal is large enough, ghasts can teleport through it and enter the overworld.
- In the early days of the ghast, the fireball texture was, weirdly enough, a snowball.
- A rebound fireball will instantly kill a ghast on impact, no matter how much health the ghast has.
- If a Mob Spawner is made to spawn a ghast, then the ghast model will be bigger than the frame.
- Knocking a fire charge back toward a ghast and killing it will earn the Return To Sender achievement/advancement.
- Oddly enough, iron golems will not attack ghasts. This may be because of their explosive attacks.