You could look at John Constantine, Dr. Fate or Ghost Rider from comics as potential Warlocks. Anyone that made a deal for power and is now burdened by their pact.
My advice: Talk to the DM and role play out the making of your pact. You don't have to figure out all the details, but the DM should be clear on why the Patron signed the pact - and the main terms of the pact. Then, figure out what your PC thinks about the pact and whether they want to escape it or not. Warlocks really shine when the DM and the player come together to have the Patron and Pact mean something. If you want to know what I mean, play Baldur's Gate 3. Compare Wyll's storyline as a warlock to the PC warlock storyline that you hand craft.
A GOO warlock can be a fun blade pact warlock. I played that early in 5E. However, a lot of people felt it was underpowered, so WotC introduced the Hexblade to make the pact of the blade work better. You won't be on the leading edge in power if you go GOO Blade Pact warlock - but it can still be a lot of fun. I enjoyed my character, Lipphil Vecraftlo.
As for alignment and personality - they can be pretty much anyone. You just have to figure out why they signed the pact if they're lawful good with an evil patron or otherwise have a personality that would be adverse to signing a pact. When the personality is in conflict with the idea of signing a pact it might seem like a problem - but I think that is storytelling gold that can give you and the DM excellent opportunities to tell great stories about why the PC went against their nature in such a significant way.
Ghost Rider is pretty solidly warlock-esque, yeah.
I'll offer a different suggestion, one that definitely isn't really a warlock, but that has a lot of the trappings of being one:
Darth Vader.
He's a wielder of dark powers who serves the will of some distant master, and at some point he realizes his master is just using him, and must be destroyed.
Bit hard to say, true, proper eldritch horror is pretty rare in fiction other than as an enemy to fight. Being a warlock tied to one is almost always a villainous trope outside of D&D. I mean, most "warlock"-like characters in fiction are villains or, at best, tragic, doomed protagonists, but Great Old One type beings are a special flavor of terribad.
The closest I can think of is Miraak, from Skyrim, because of his service to Hermaeus Mora, the Daedric Prince of knowledge, who is represented as being a pretty eldritch, tentacular thing.
You're flirting with the boundaries of sanity and reality. That implies either you have a mind like a steel trap, which can filter through all the BS and distortion to get to the truth...or you're a bit crazy. Possibly both, at turns.
It can, you can make any patron work, but it won't be as strong as Hexblade with Blade Pact. Perhaps, once the 2024 books come out, that might change. That said, I wouldn't say Great Old One is bad for Blade Pact--it's just that Hexblade is amazing for it.
For the patron? Chaotic Neutral to Chaotic Evil, generally speaking. Remember, these things are basically Cthulhu. They aren't nice, and they usually intend destruction.
The warlock, however, can be any alignment. Perhaps they were manipulated into forming the pact, or got caught in a horrible situation and effectively coerced (e.g. "accept this terrible pact or die"). Perhaps they're a death-cultist seeking to tear reality apart so that nothing can ever live again. Perhaps they're an archaeologist who dug too deep in a strange, spiral-shaped ruin and unearthed something that should have stayed buried. Perhaps they're an innocent child raised by Not!Cthulhu-worshipers, who doesn't think all this eldritch stuff is a problem.
There are all sorts of stories you can tell with a Great Old One warlock.
You could look at John Constantine, Dr. Fate or Ghost Rider from comics as potential Warlocks. Anyone that made a deal for power and is now burdened by their pact.
My advice: Talk to the DM and role play out the making of your pact. You don't have to figure out all the details, but the DM should be clear on why the Patron signed the pact - and the main terms of the pact. Then, figure out what your PC thinks about the pact and whether they want to escape it or not. Warlocks really shine when the DM and the player come together to have the Patron and Pact mean something. If you want to know what I mean, play Baldur's Gate 3. Compare Wyll's storyline as a warlock to the PC warlock storyline that you hand craft.
Very little of this is applicable to Great Old One warlocks, though. GOOs are not devils offering written pacts signed in blood. They are Lovecraftian monstrosities with (per the PHB) "incomprehensible motives", who may be "unaware of the existence" of their warlocks or
"entirely indifferent" to them.
A GOO "pact" is unlikely to take the form of an explicit bargain. More likely, it would be the result of the warlock making contact with the Great Old One (perhaps intentionally, perhaps not). Exposure to such a being grants the warlock strange powers, at the price of warping their mind and body. Think of how, in BG3, you can
consume tadpoles and eventually become part illithid.
Very little of this is applicable to Great Old One warlocks, though. GOOs are not devils offering written pacts signed in blood. They are Lovecraftian monstrosities with (per the PHB) "incomprehensible motives", who may be "unaware of the existence" of their warlocks or
"entirely indifferent" to them.
A GOO "pact" is unlikely to take the form of an explicit bargain. More likely, it would be the result of the warlock making contact with the Great Old One (perhaps intentionally, perhaps not). Exposure to such a being grants the warlock strange powers, at the price of warping their mind and body. Think of how, in BG3, you can
Actually...there's nothing keeping a GOO Patron from making explicit bargains.
GOO Patrons are the more likely to have inactive involvement with patrons.
But GOO patrons include dead gods, imprisoned gods, and far realm entities like the infested Stars that the GOO pact same from in 4e.
Caiphon, Hadar and Acamar will blink in the night sky a secret code and will sent strange dreams. Warlocks who follow these sign do so act their own peril.
The 4e Stars IMHO are the best fit to how a GOO pact and patron relationship would be in D&D. The Stars, these powerful non-dieties, contact the warlocks in dreams and visions to give them insight and information while sucking the life, souls, will, or sanity of their beings around the warlock and their enemies. And the warlock slowly has the mind altered so much that they can't realize what is happen or do realize but are now helpless to stop it. What can scare a god? An unreachable being that can turn people into walking beacons of insanity and death.
Because that's the thing. You can't research to know if the GOO pact is explicit without entering the pact accidentally and being driven insane to the point to think you made the pact.
Very little of this is applicable to Great Old One warlocks, though. GOOs are not devils offering written pacts signed in blood. They are Lovecraftian monstrosities with (per the PHB) "incomprehensible motives", who may be "unaware of the existence" of their warlocks or
"entirely indifferent" to them.
I think you're treating a "might" clause as a definite claus here. There are a lot of beings in Lovecraft Mythos that make deals to gain power. While there are many options available, it is incorrect to say that an intentional pact would not be applicable. It very well could be.
A GOO "pact" is unlikely to take the form of an explicit bargain. More likely, it would be the result of the warlock making contact with the Great Old One (perhaps intentionally, perhaps not)... Exposure to such a being grants the warlock strange powers, at the price of warping their mind and body. Think of how, in BG3, you can ...
Again, this is one path specifically allowed in the PHB, but not the only path ... and when one path is labeled as something that "might" happen, I tend to think the other option would not also be labeled "unlikely". Might usually conveys a lower probability rather than a higher one. When as say something might happen, it is usually to dissuade someone from believing it is impossible. If it is likely to happen, we'd tend towards words likely likely, probably or certainly.
If you look in BG3 you can see clear examples of
beings making deals with Far Realms inspired entities to gain power, safety or other boons in exchange for service.
Londo Mollari of Babylon 5 would be another example of someone that makes a deal with an Elder God type in exchange for power. I used that as an inspiration for a PC early in 5E that died too quick - He was a scholar that was infected by a parasite that was the actual one performing the magic. The scholar was a normal mortal, essentially. The thing would compel the scholar to do what it wanted him to do if the scholar was not compliant. The DM and I had fun with it briefly... when the thing compelled the scholar to do stuff, I'd leave until the DM called me back so that I would have no idea what took place while compelled. The PC, unfortunately, took a critical hit from a giant when he was low on hps .... and went straight to negative max hp ... sigh
I think you're treating a "might" clause as a definite claus here. There are a lot of beings in Lovecraft Mythos that make deals to gain power. While there are many options available, it is incorrect to say that an intentional pact would not be applicable. It very well could be. Again, this is one path specifically allowed in the PHB, but not the only path ... and when one path is labeled as something that "might" happen, I tend to think the other option would not also be labeled "unlikely". Might usually conveys a lower probability rather than a higher one. When as say something might happen, it is usually to dissuade someone from believing it is impossible. If it is likely to happen, we'd tend towards words likely likely, probably or certainly.
If you look in BG3 you can see clear examples of
beings making deals with Far Realms inspired entities to gain power, safety or other boons in exchange for service.
Londo Mollari of Babylon 5 would be another example of someone that makes a deal with an Elder God type in exchange for power. I used that as an inspiration for a PC early in 5E that died too quick - He was a scholar that was infected by a parasite that was the actual one performing the magic. The scholar was a normal mortal, essentially. The thing would compel the scholar to do what it wanted him to do if the scholar was not compliant. The DM and I had fun with it briefly... when the thing compelled the scholar to do stuff, I'd leave until the DM called me back so that I would have no idea what took place while compelled. The PC, unfortunately, took a critical hit from a giant when he was low on hps .... and went straight to negative max hp ... sigh
Personally, I think the Shadows are really obviously Fiend-type beings rather than GOO. They aren't even slightly incomprehensible (nor are the Vorlons), they just couch all of their really quite plain motives behind seventeen unnecessary layers of metaphor. There's always a clear reason why they're doing what they're doing, especially when it comes to Londo. (Indeed, the fact that their 'avatars' are reduced to practically child-like dialogue after getting told off by Delenn and Sheridan--"Will you...come with us?" [...] "Then...we will not be alone?"--shows to me that, for all their metaphor, their desires remain very comprehensible.)
The closest example (of media I actually know, e.g. I've never read Bartimeus books, I never watched Buffy, etc.) mentioned above is Zorg from The Fifth Element. Even there, the horrible thing, "Mister Shadow," comes across as being quite aware of its servants and, again, having pretty straightforward, albeit evil, motives. It wants to destroy all life, and is cunning enough to manipulate others into helping it achieve these aims. However, it only speaks once, generally is beyond comprehension other than "absolute evil," and has weird powers that don't really seem to be traceable to a physical cause (the "black goo" stuff, mostly.) So you could argue that its appearance of understandable-ness is simply because it's a particularly malicious eldritch horror, a la Hastur, rather than because it really is all that comprehensible to us.
Outside of outright Lovecraftian stories (or the seeds from which his work grew, like Robert W. Chambers' reinterpretations of Ambrose Bierce's Hastur), however, it's pretty rare to find things that truly fit the mold of Great Old One type beings, rather than the other two main patrons, Fiend or Archfey. Alien beings prior to the 19th century tended to be fairies, which while certainly alien were not that kind of alien. Some of it, I suspect, comes from the flowering of scientific understanding in the 18th and 19th centuries, but some of it also comes from the ennui of the industrial era and the horrors of 19th and early 20th century warfare. Some likely also comes from the long-term hegemonic status of the Abrahamic religions in Europe and the Near East and the "god is dead" stuff that had cropped up in the 19th and early 20th. In prior millennia, you could have your (good!) gods and the enemy's (evil!) gods, but that just gets bound up with the Fiend pact now (note where many demons'/devils' names come from.) Great Old One stuff is of a different caliber--the yawning void itself, given sapience. An entity that truly would prefer to destroy everything, as opposed to wanting to topple the existing order and replace it with a distinct but still existing order.
