BOZ
Creature Cataloguer
Here is a monster that appeared in a very early issue of Dragon mag, and stat-wise appears to predate even 1E AD&D. diaglo would be proud. 
This, of course, may make a greater challenge for us, as the distance between editions is great. For the most part, I will defer to this earlier conversion, except where we find cause to change things.
Death Angel
Medium-size Outsider
Hit Dice: 7d8+14 (45 hp)
Initiative: +5 (+1 Dex, +4 Improved Initiative)
Speed: 30 ft, fly 60 ft (good)
AC: 20 (+1 Dex, +9 natural)
Attacks: Scythe +11/+6 melee
Damage: Scythe 2d4+6 (crit x4) and 1d4 permanent Constitution drain
Face/Reach: 5 ft by 5 ft/5 ft
Special Attacks: Constitution drain, final death, create death angel
Special Qualities: Damage reduction 20/+2, SR 20, telepathy, darkvision 60 ft, reanimation
Saves: Fort +7 Ref +6 Will +9
Abilities: Str 18 Dex 13 Con 15 Int 18 Wis 18 Cha 14
Skills: Bluff +12, Concentration +12, Escape Artist +8, Hide +8, Listen +14, Move Silently +11, Search +14, Sense Motive +14, Spot +14
Feats: Improved Initiative, Power Attack
Climate: Any land
Organization: Solitary
Challenge Rating: 08
Treasure: None
Alignment: Always neutral
Advancement: 8-10 HD (Medium-size); 11-21 HD (Large)
The death angel represents one of two facets when it appears before a creature; either to warn that creature of its impending doom or to take the life of the creature. A death angel is often employed by deities, powerful outsiders, and liches.
A death angel appears as a 6-foot tall humanoid in flowing crimson, scarlet, or black robes. Its head and face is covered in a golden helm. Two large golden wings protrude from its shoulders.
COMBAT
The angel of death battles its foes with its scythe. It concentrates its attacks on the one it was sent to kill (if indeed it was sent to kill a creature). It is not oblivious to its intended target's allies and does not act rash or stupidly in combat. If it must disperse with the target's allies before slaying its target, then so be it.
A slain death angel evaporates in a puff of acrid smoke.
Constitution Drain (Su): Any creature hit by the death angel's scythe suffers permanent Constitution drain. At Con 0, the creature dies.
Final Death (Su): Any humanoid slain by a death angel is usually dead and gone. Attempts to raise or restore a dead creature are met with failure unless the spell used is wish, miracle, or true resurrection, but there is a 50% chance that even such powerful magic fails.
Create Death Angel (Su): A humanoid creature slain by a death angel can be "raised" as a death angel under control of the death angel that killed it. This is similar to the create spawn ability of some undead creatures. A creature raised as a death angel possesses none of the abilities it had in life and remains enslaved until its master is slain.
Telepathy (Su): A death angel can communicate telepathically with any creature within 100 feet that has a language.
Reanimation (Ex): A death angel that is slain will return to life in 1d3 days and continue its pursuit of the original target unless a remove curse (cast by a 15th-level caster), wish, or miracle is cast on the spot where the death angel was slain.
1977 Wizards of the Coast, Inc.
Originally found in Dragon #6 (John Sullivan)

This, of course, may make a greater challenge for us, as the distance between editions is great. For the most part, I will defer to this earlier conversion, except where we find cause to change things.
Death Angel
Medium-size Outsider
Hit Dice: 7d8+14 (45 hp)
Initiative: +5 (+1 Dex, +4 Improved Initiative)
Speed: 30 ft, fly 60 ft (good)
AC: 20 (+1 Dex, +9 natural)
Attacks: Scythe +11/+6 melee
Damage: Scythe 2d4+6 (crit x4) and 1d4 permanent Constitution drain
Face/Reach: 5 ft by 5 ft/5 ft
Special Attacks: Constitution drain, final death, create death angel
Special Qualities: Damage reduction 20/+2, SR 20, telepathy, darkvision 60 ft, reanimation
Saves: Fort +7 Ref +6 Will +9
Abilities: Str 18 Dex 13 Con 15 Int 18 Wis 18 Cha 14
Skills: Bluff +12, Concentration +12, Escape Artist +8, Hide +8, Listen +14, Move Silently +11, Search +14, Sense Motive +14, Spot +14
Feats: Improved Initiative, Power Attack
Climate: Any land
Organization: Solitary
Challenge Rating: 08
Treasure: None
Alignment: Always neutral
Advancement: 8-10 HD (Medium-size); 11-21 HD (Large)
The death angel represents one of two facets when it appears before a creature; either to warn that creature of its impending doom or to take the life of the creature. A death angel is often employed by deities, powerful outsiders, and liches.
A death angel appears as a 6-foot tall humanoid in flowing crimson, scarlet, or black robes. Its head and face is covered in a golden helm. Two large golden wings protrude from its shoulders.
COMBAT
The angel of death battles its foes with its scythe. It concentrates its attacks on the one it was sent to kill (if indeed it was sent to kill a creature). It is not oblivious to its intended target's allies and does not act rash or stupidly in combat. If it must disperse with the target's allies before slaying its target, then so be it.
A slain death angel evaporates in a puff of acrid smoke.
Constitution Drain (Su): Any creature hit by the death angel's scythe suffers permanent Constitution drain. At Con 0, the creature dies.
Final Death (Su): Any humanoid slain by a death angel is usually dead and gone. Attempts to raise or restore a dead creature are met with failure unless the spell used is wish, miracle, or true resurrection, but there is a 50% chance that even such powerful magic fails.
Create Death Angel (Su): A humanoid creature slain by a death angel can be "raised" as a death angel under control of the death angel that killed it. This is similar to the create spawn ability of some undead creatures. A creature raised as a death angel possesses none of the abilities it had in life and remains enslaved until its master is slain.
Telepathy (Su): A death angel can communicate telepathically with any creature within 100 feet that has a language.
Reanimation (Ex): A death angel that is slain will return to life in 1d3 days and continue its pursuit of the original target unless a remove curse (cast by a 15th-level caster), wish, or miracle is cast on the spot where the death angel was slain.
1977 Wizards of the Coast, Inc.
Originally found in Dragon #6 (John Sullivan)