The closest I can think of to something like that is Azimer the 19th level lich in
the 1e Forgotten Realms Campaign Setting's sample adventure (reprinted from Dragon 95 with pregens ranging from level 5 to a single 8th level thief) who is explicitly addled and insane and starts off not being hostile and is presented as a roleplaying challenge as the way to successfully deal with him. He does not have fireball or lightning bolt so no 19d6 AoEs and his prepared ninth level spell is single target imprisonment, but he still has cloudkill and death spell (which will no save kill a number of PCs) and a bunch of power words and the DM is explicitly told to expect him to wipe the PCs if it comes to combat.
Azimer is still well equipped with
spells, and his condition still allows him
to cast them (though he has a 1%
chance per level of a spell attempted of
blowing the spell so that it does not go
off). His current spells are as follows:
magic missile (x3), read magic, shield,
continual light, ESP levitate, magic
mouth, wizard lock, dispel magic, gust
of wind, hold person (x2), suggestion,
dimension door (x2), fire trap, wall of
fire, wall of ice, cloudkill, feeblemind,
hold monster (x2), wall of force, antimagic
shell, death spell, repulsion, cacodaemon,
power word stun, reverse
gravity, Ottos irresistible dance, power
word blind (x2), and imprisonment.
Note that Azimers magic missile
spells each firing ten missiles that do 2-
5 hp damage apiece) may be directed at
separate targets if the lich so wishes.
Azimer will employ these first, interspersing
them with any defensive spells
he deems necessary (e.g., feeblemind
on spellcasters, hold person or hold
monster on charging attackers, or
reverse gravity on a group of attackers,
anti-magic shell if he faces many spellcasters,
and so forth). Azimer will use
dimension door to get into area 29 if
seriously threatened.
In
I2 Tomb of the Lizard King with level 5-7 PCs the vampire lizard king who is a level 9 MU (so gets a 5th level spell) has both fireball and lightning bolt and explicitly is said to start off with cloudkill which will be save or die saves for a 20x40 persistent cloud.
In
I10 The House on Gryphon Hill the lich Azalin does not have fireball or meteor swarm, but he does have the 7th level delayed blast fireball which will do 18d6+18 to the 8-10th level PCs where the pregens range from 18-75 hp.
Azalin the Lichs Spells
1st Level: charm person (x2), diminish, magic missile,
prot:good
2nd Level: darkness 15R, det. invisible, vocalize, web,
wizard lock
3rd Level: dispel magic, fly, prot:norm.missiles, slow,
suggestion
4th Level: dimension door (x2), ice storm, minor globe,
bestow curse
5th Level: animate dead, interposing hand, feeblemind,
wall of stone, monster summons III (1-4 wolves)
6th Level: anti-magic shell. invisible stalker, contingency
7th Level: delayed fireball, teleport w/o error (x2)
8th Level: clenched fist, monster summons IV (2 wraiths)
9th Level: energy drain
Strahd in I6 and I10 has fireball and lightning bolt.
In WG7 Castle Greyhawk there is a lich 20 he has a 20d6 lightning bolt and 20d4+20 cone of cold prepared.
Those and the lich in D1-2 who is loaded for bear are the only ones I can think of from 1e adventures.
Do you have specific other AD&D examples you are thinking of?