Alucard

Legendary Resistance (3/Day, or 4/Day in Lair). If Alucard fails a saving throw, he can choose to succeed instead. 

Lizard Climb. Alucard can climb difficult surfaces, including along ceilings, without needing to make an ability check.

Regeneration. Alucard regains 30 hit points at the start of his turn. If he takes damage from sunlight or sunfire, this trait doesn’t function at the start of his next turn.

Supernatural Senses. Magical darkness doesn’t impede Alucard’s darkvision. Alucard can hear a heartbeat from up to 250 feet away.

Alucard’s Weaknesses. Alucard has these weaknesses:

Sunlight. If Alucard starts his turn in sunlight and does not have the Ring of the Moon equipped, he takes 20 Radiant damage. While affected by sunlight, he has Disadvantage on attack rolls and ability checks and cannot use his mist form, teleport, or shapeshift.
Sunfire. Alucard is vulnerable to these spells: Dawn, Sunbeam, Sunburst, and any other spell or item that uses sunlight or sunfire to cause damage.
Fatality. Alucard can only be permanently destroyed in one specific way: when his regeneration is halted, his entire body must be incinerated with sunfire and decapitated with a holy sword, simultaneously.

Multiattack. Alucard makes two Hellfire Spear attacks and uses Bite; or makes a Hellfire Spear attack and casts one at will spell.

Hellfire Spear. Melee or Ranged Attack Roll: +12, reach 5 ft. or range 60 ft. Hit: 12 (1d12 + 6) Piercing damage plus 22 (4d10) Fire damage. Hit or Miss: The spear magically returns to Alucard’s hand immediately after a ranged attack.

Bite. Constitution Saving Throw: DC 21, one creature within 5 feet that is willing or that has the Grappled, Incapacitated, or Restrained condition. Failure: 8 (1d4 + 6) Piercing damage plus 17 (5d6) Necrotic damage. The target’s Hit Point maximum decreases by an amount equal to the Necrotic damage taken, and Alucard regains Hit Points equal to that amount. Success: 8 (1d4 + 6) Piercing damage.

Spellcasting. Alucard casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (+15 to hit, spell save DC 23):

At will: Fireball, Fog Cloud (level 3 version), Guiding Bolt (level 3 version), Lightning Bolt, Moonbeam, Scorching Ray (level 3 version), Shapechange (Beast form only, no Concentration required to maintain the spell), Suggestion

1/day each: Call Lightning, Chain Lightning, Flame Strike, Fount of Moonlight, Raise Dead, Wall of Fire

2/day: Crown of Stars, Delayed Blast Fireball, Maddening Darkness, Storm of Vengeance

Teleport. Alucard magically teleports, along with any equipment he is wearing and carrying, up to 120 feet to an unoccupied space within darkness, fog, or a storm.

Charm (Recharge 5–6). Alucard casts Charm Person, requiring no spell components and using the same spellcasting ability as Spellcasting, and the duration is 24 hours. The Charmed target is a willing recipient of Alucard’s Bite, the damage of which doesn’t end the spell. When the spell ends, the target is unaware it was Charmed by Alucard.

Mist Form. If Alucard isn’t affected by sunlight, he shapeshifts into a Medium cloud of mist (Speed 5 ft., Fly Speed 20 ft. [hover]), or returns to his true form. Anything he is wearing transforms with it.

While in mist form, Alucard can’t take any actions, speak, or manipulate objects. He is weightless and can enter an enemy’s space and stop there. If air can pass through a space, the mist can do so, but it can’t pass through liquid. He has Resistance to all damage, except the damage he takes from sunlight.

Legendary Action Uses: 3 (4 in Lair). Immediately after another creature’s turn, Alucard can expend a use to take one of the following actions. Alucard regains all expended uses at the start of each of his turns.

Deadly Strike. Alucard moves up to double his Speed, and makes one Demonic Sword or Holy Sword attack. 

Hypnotic Gaze. Wisdom Saving Throw: DC 23, one creature Alucard can see within 120 feet. First Failure: Alucard casts Command. Second Failure: Alucard casts Antagonize. Third Failure: Alucard casts Dominate Person.

Teleport. Alucard uses his Teleport action.