Deathlock

Deathlocks were undead spellcasters bound to serve a master. They were usually the remains of warlocks, reanimated by their patrons after failing to fulfill their part of a pact, but could also be created by necromancers.

Personality
Deathlocks did not have any goals that they had in life, aside from fulfilling their patron's desires. This urge to serve their patron was overpowering and consumed their every thought.

Abilities
All forms of deathlock had an innate spellcasting ability that allowed them to cast detect magic, disguise self, and mage armor.

Beyond their innate spellcasting ability, deathlocks retained some of the spells of their living counterpart. These typically included the following:
 * arms of Hadar, chill touch, dispel magic, eldritch blast, hunger of Hadar, hold person, invisibility, mage hand, and spider climb.

However, the arsenal of spells that a deathlock had could vary widely depending upon what patron they had.

Masterminds
Deathlock masterminds had access to a larger arsenal of spells than the average deathlock. These additional spells typically included blight, counterspell, crown of madness, darkness, dimension door, fly, hold monster, minor illusion, and poison spray. Though again, this arsenal could vary widely depending upon what patron they had.

Besides spells, a deathlock mastermind was capable of shooting necrotic bolts at their enemies.

Patron Spells
Those with with an Archfey patron were capable of casting the spells blink, faerie fire, hunger of Hadar, hypnotic pattern, phantasmal force, and sleep. In addition to these, a mastermind had access to the spells dominate beast, dominate person, and greater invisibility, and seeming.

Those with a Fiend patron were capable of casting the spells blindness/deafness, burning hands, command, fireball, hellish rebuke, and scorching ray. In addition to these, a mastermind had access to the spells fire shield, flame strike, stinking cloud, and wall of fire.

Those with a Great Old One patron were capable of casting the spells armor of Agathys, detect thoughts, dissonant whispers, hunger of Hadar, Tasha's hideous laughter, and phantasmal force. In addition to these, a mastermind had access to the spells clairvoyance, dominate person, Evard's black tentacles, sending, and telekinesis.

Wight
Deathlock wights were sensitive to the light of the sun and could drain the life from living creatures. Those slain by their draining touch would arise as a zombie under its command. And much like a mastermind, they could shoot necrotic bolts.

They lacked the spells of their living counterparts, though could cast the trio of spells that all deathlocks could innately do. In addition, deathlock wights could innately cast fear, hold person, and misty step.

Variants

 * Masterminds: Deathlock masterminds were deathlocks that had been granted more freedom and power, as they were also charged with recruiting and commanding others to serve their patrons' goals.
 * Wights: Deathlock wights were deathlocks that had been punished by certain types of patrons or necromancers by being transformed into husks of their former selves, halfway between a warlock and a wight. Some were known to try and gather other undead creatures under their serivce.