I have played a number of games here...and I have NEVER encountered an enemy Warlock

[Vos]

OK so that is about 5 or 6 DMs. I have never had to fight a warlock. I am just now playing one and it struck me.
is it one class to many to keep up with? Are they cheesy? Are they two powerful? Overlooked?

I could see a Kobold with a D10 attack might be deadly at first level. How about at 4th level? It's now a D10 +4 (or more with Hex).

Is this just my luck with DMs and the rest of you are having to kill the pesky locks?

[Zacchaeus]

What you come up against will depend on what NPCs are in the module that you're playing in. I can't remember all the NPCs in all the modules but I'm pretty sure there are a few that have warlocks NPC.

[LordEntrails]

Dragon heist has a enemy warlock, if you end up going against the faction that contains it.

It was very challenging for my players at the time.

[Marquis_de_Taigeis]

NPC’s don’t need to follow class structure when being made and so what might be closer to a warlock in capabilities might be describe more like a cleric

[LordEntrails]

Volo's have a bunch of warlock NPCs. I don't think they are identical to an equivalent PC level warlock, but they are certainly similar.

[Hyperventilator]

I'm just in the middle of making custom spellcaster NPCs using MM's and Volo's NPCs as starting points. A warlock is included

The party could encounter a drow warlock, orc warlock, or a dragonborn warlock - and I can use the same stat block for all of them. That way, I can occasionally throw a spellcaster NPC into an encounter to challenge the party's spellcasters with a Hold Person here, a Hypnotic Pattern there, breaking their concentration.

[Vos]

Update: I did not speak with my DM. But we did encounter a settlement of Kuo-toa fish people and 4 of them were first level locks. They were focusing on one character at a time with 1D10 each. They didn't hit a lot but used the 120 foot range to stay well away from the fight. No bolts ever went my way, and I'm the guy who bought a Brooch of Shielding (with its resistance to Force Damage).

they stayed close together coordinating hits, but a fireball took them out.

[similarly]

As a GM, I've created as NPCs and enemies:
* evil warlocks
* an evil druid
* The Teenage Mutant Ninja Tortles
* The Universal Classic Monsters (in my game, Manshoon's followers messed up a ritual to bring him back from the dead, and accidentally created 7 different Manshoons: Werewolf, Vampire, Flesh Golem (Frankenstein), Mummy, an air elemental (the invisible man), a Jekyll and Hyde creature and a Creature from the Black Lagoon.
* An albino gnoll named Mr. Peabody who traveled with a young human boy named Sherman

and I'm sure I had a few other ridiculous jokes in there.