Legion

Legion is from Castlevania Symphony of the Night and is the best monster so far in the Castlevania series. Legion is a floating sphere of naked bodies that act as protection for the tentacled parasite underneath.
I give this monster 9 out of 10 Tentacles.

Albert Simon

This is Albert Simon, or Messiah,  from the game Shadow Hearts. Albert Simon was a student of the legendary philosopher and monk Roger Bacon. Roger saw great things in Albert and taught him laws, philosophy, science, astronomy and alchemy. Albert had the makings of a great civil-rights leader, and Bacon looked forward with great eagerness to the world Albert would help forge. But in time, Albert began to question the “divine right” of the ruling class aristocrats to manipulate, sacrifice and generally mistreat the masses. When Bacon attempted to moderate Albert's views and encouraged him to let the world be as it was for the time, Albert lost faith in Roger and went to the Vatican to charge Roger with heresy for his tolerance of the corrupt. But it was Albert who the church condemned as a heretic for questioning “divine right” in the first place. Albert was locked away for years before his release. The years changed Albert, and he became a far more cynical person, especially of the church. Albert Simon's standard attack is potent telekinesis. He is also fond of using dark incantations to excel his mystical strength. Albert has advanced healing capabilities, but only on himself. Albert can also merge with entities, such as angels or demons with a nigh-indomitable will that resists possessions from said entities. Albert has an incredibly powerful spell called “Revelation” which can instantly put a single target an inch away from death. Albert has an ability to teleport himself and other willing or unconscious subjects over vast distances. He has the power to fly, though at a limited speed. Albert seems to have a force-field as well that can protect against god level power. Albert also has the power to raise the dead as undead and summon god level creatures. Albert Simon transforms himself into this monster, the Messiah during his last encounter with the heroes. The music that plays when you fight the Messiah  "Demons Gig" is the ultimate boss music. I give Albert  8 out of 10 Tentacles.

The Creeper

The Creeper is a monster who appears in The Suffering: Ties That Bind. He was formerly known as Luther Stickwell, an infamous killer pimp. He started murdering his own prostitutes before turning his attention to any female he came across, eventually killing between 50 and 200 women and becoming the basis of an urban legend. The Creeper can be found roaming through dark alleys, or down in the sewer system surrounded with the dead bodies of seemingly hundreds of women. The Creeper's most infamous line is "Blood is the best lubricant." I give this monster 6 out of 10 Tentacles.

Demogorgon

This version of the Demogorgon is from Dungeons and Dragons. The Demogorgon appears as an 18-foot-tall, hermaphroditic demon with a somewhat humanoid form. Two mandrill heads sprout from his twin snake-like necks, and his arms end in long tentacles. His two heads have individual minds, called Aameul (the left head) and Hethradiah (the right head). Demogorgon is a monster whose very name is taboo. I give this monster 9 out of 10 Tentacles.

Necromorph Guardian

Nercomorph Guardian is a great monster from the games Dead Space 1 and 2. This monster was once human, and now exists only to be stuck on a wall and try and kill things with his tentacles. I think the design is fantastic but since it can't move, I give this monster 6 out of 10 Tentacles.

Huge Frogger

Huge Frogger is a monster from the Super Nintendo game King of Monsters 2. He is the size of Godzilla, can teleport, and can shoot beams from his mouth.When Huge Frogger knocks you down, he has an awesome watery laugh. His in game music is pretty good, considering its Super Nintendo. 4 out of 10 Tentacles.

Arakune

Arakune is from the fighting video game Blazblue. Arakune is my favorite fighting game character of all time. He was once human, but studying a place called the boundary has transformed him into a blob like creature, that can summon monster insects. He is utterly insane and can barely communicate. I give my favorite fighting video game character 10 out of 10 Tentacles.