This started as a feat that attempted to convert the Add On- Vampire race by HomestewsAndHousebrews to a feat, as well as give it some strengths to balance out its many weaknesses, but slowly became an amalgam of all sorts of vampire races.

Your character has contracted Sanguinare Vampiris (Vampire disease) or been turned by another vampire. Many changes, both good and bad, will come from this metamorphosis. As a creature of the night you fear the daylight and revel in darkness. 

Age

Your aging slows to a halt. You are unable to age any further than the exact age you were when you became a vampire.

Revel in Darkness

As a creature of the night you have become accustomed to sneaking and hiding to catch your prey. You gain proficiency in stealth and double proficiency in stealth at night.

Darkvision

Accustomed to hunting at night, you have superior vision in dark and dim conditions. You can see in dim light within 120 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

Blood Hunger

You have a Blood craving to satisfy.  You must feed, taking at least one vial, or 4 ounces, of blood, into yourself every 48 hours, or begin to take levels of exhaustion. While that is just enough to sustain you, you still feel the urge to drink and may still appear twitchy or ravenous in the heat of battle or when treating a wounded ally. A pint, such as that contained within a flask is considered a healthy amount, enough to keep you sustained while also suppressing your less civilized behavior.

Invigorated

Like a shark tasting blood, quenching your thirst makes you go into a frenzied state for a short while after. After drinking blood you can choose to gain the following benefits as a free action.

Spider Climb. You gain a climbing speed equal to your walking speed and gain the ability to move up, down, and across vertical surfaces and upside down along ceilings, while leaving your hands free.

Heightened Senses. In a frenzy, your reflexes and senses have been improved. You have advantage on all dexterity and perception checks.

These benefits are active for 5 minutes and this ability can be used 3 times per long rest. This number increases to 4 at 6th level, 5 at 11th level, and 6 at 16th level.

Vampiric Aura

The Vampire emits a powerful aura that makes all who are not strong enough to resist it want to impress the vampire and will practically do whatever the vampire requests. You can cast Charm Person as a first level spell per long rest without expending a spell slot. This goes from first to second level at level 3. Charisma is your spellcasting ability for this spell.

Drain Essence

Once per day as a bonus action you may bite with the intent to drain another creature of its life. The creature you are biting must either be willing, grappled, restrained, or incapacitated by you. If an unwilling creature bitten this way is able to successfully escape restraint, grappling, or incapacity the effect ends. An unwilling creature must make a wisdom saving throw, the DC for this saving throw equals 8 + your intelligence modifier + your proficiency bonus. A creature takes 2d6 necrotic damage per turn on a failed save, and half as much damage on a successful one. The damage increases to 3d6 at 6th level, 4d6 at 11th level, and 5d6 at 16th level. Using Drain Essence also allows you to drink the blood from your victim, giving you 1d4 vials, or 4 ounces, of blood. After you use this ability once you can’t use it again until you complete a  long rest.

The target’s hit point maximum is reduced by an amount equal to the necrotic damage taken, and the vampire regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. A humanoid slain in this way and then buried in the ground rises the following night as a vampire with all of the abilities this feat variant grants.

Misty Escape

When you drops to 0 Hit Points you transform into a cloud of mist instead of Falling Unconscious, provided that it isn't in sunlight or running water. If you can't transform, you are destroyed.
While you have 0 Hit Points in mist form, you can't revert back to your vampire form, and you must reach a coffin within 2 hours or be destroyed. Once in your resting place, you revert to your vampire form. You are then Paralyzed until you regains at least 1 hit point. After spending 1 hour in your resting place with 0 Hit Points, you regain 1 hit point.

Vampire Weaknesses

You have the following flaws:

Vampiric Nature. You are now considered both an undead and a humanoid. As an undead, you no longer need to breathe, you are immune to disease, and you are resistant to necrotic damage. However, due to your unholy nature, you take double damage from radiant damage.

Forbiddance. You can't enter a residence without an invitation from one of the occupants. A sign on the outside of a building saying something like "open for business" will also allow you to enter a building.

Harmed by Running Water. You take 20 acid damage if you end your turn in running water. This acid damage ignores resistance and immunity to acid damage that may be granted by your base race.

Stake to the Heart. If a piercing weapon made of wood is driven into your heart, you become incapacitated until the stake is removed.

Sunlight Hypersensitivity. You take 20 burning damage when you start your turn in sunlight. This burning damage ignores resistance and immunity to burning damage that may be granted by your base race. While in sunlight, you have disadvantage on attack rolls and ability checks.

(Optional)

Unless starting with this feat, it is recommended that you trickle these abilities and weaknesses to the player over a period of time, to illustrate the worsening of the disease, as opposed to the player just waking up with these powers one day.

-This feat has an upgrade at level 8. See "Master Vampire" for more info.