Giant Ghost

The Giant Ghost (also known as Skull Lord, Large Ghost, or Great Ghost) is a ghost taking the form of a giant skull. It attacks by erratically approaching the hero, occasionally pausing before delivering a fast, dashing bite.

Castlevania: Rondo of Blood
First appearance in the series. The Big Ghost makes an impressive introduction midway through the first section in Stage 3' of Rondo of Blood, where the screen suddenly stops scrolling and this entity slowly emerges in the distance, soon arriving where the hero stands. It is a phantasmagorical aberration with three eyeballs, two in their respective eye sockets and a third on its forehead, and attacks by hovering around the screen while three smaller phantom skulls circle around it. It then slowly homes toward the hero attempting to inflict physical damage with its massive size. It can't be harmed by any normal means other than attacking the eyeballs themselves. Fortunately, each one can only sustain a single hit, but due to the ghost's movements and size, this fight can be either extremely easy or considerably difficult, depending on the player's skill and current sub-weaponry.

If playing as Richter, bringing the Axe, Cross or Dagger are all very good choices. If playing as Maria, Seiryuu is definitely the best option. In fact, a single dragon is enough to destroy all three eyeballs if aimed properly.

Castlevania: Symphony of the Night
The Skull Lord makes an impressive appearance in Symphony of the Night, enriched by the innovative various effects provided by the then new PlayStation system, like a huge sprite size, detailed design and enhanced color palette, and impressive lighting effects. It appears in the Clock Tower and the Reverse Keep and is usually seen among other smaller Phantom Skulls. It is specially weak to Holy, however, and if Alucard managed to get his hands on the Holy Rod beforehand, he may destroy the Skull Lord in a single hit, depending on his stats.

Castlevania Legends
In Legends, the Skeleton Head floats out of reach and charges to attack when Sonia's back is turned.

Castlevania: Harmony of Dissonance
In Harmony of Dissonance, the Giant Ghost's dead skull from Rondo of Blood can be found in a background of the Skeleton Cave. However, the regular version from Symphony of the Night can be found lurking in graveyards, again, among many other smaller Ghosts. This time around, it has a ghostly blue fiery aura around it, much like its smaller counterparts.

Castlevania: Aria of Sorrow
In this version, the Giant Ghost has been reinstated with its third eyeball from Rondo of Blood and also fashions a fiery aura around it. Otherwise, it attacks in the exact same manner as in other versions.

Castlevania: Portrait of Ruin
The Great Ghost from Portrait of Ruin is a hidden enemy and defeating it is the requirement for completing Wind's "Ghosts of the Desert" quest. Only one appears in the entire game and the only hint the player has to find it says that "there is a room in which many ghosts gather". To find the Great Ghost, the player must go to the rightmost-bottom room of the upper right area in Sandy Grave, where many Ghosts appear, and stay there for a considerable amount of time, killing every Ghost that comes in sight until the Great Ghost finally appears. It must be noted that the requirement for this quest can be fulfilled even before starting the quest itself; the player may kill the Great Ghost first and when they talk to Wind to start the quest, it will be already completed.

Trivia

 * In Symphony of the Night, the Skull Lord found in the Reverse Keep doesn't have eyes, unlike the one found in the Clock Tower.
 * The particular way of attacking of the Skeleton Head in Legends is very similar to the Boo enemies from the Mario franchise, which are ghosts that stand still high above while facing them but quickly home toward the hero as soon as they turn their back against them.
 * In Aria of Sorrow, the Giant Ghost is one of two enemies able to deal Dark damage (the other is the second form of Chaos).