Wow so she's the goddes of birth? I was really wondering what is her power and could have sense, but to me her character is a big interrogation for now.. maybe she will be the key to Goblin at the end.

I think tonight episodes was a big advance and I can't imagine how they will make from now, without spoil, the ending is a wow haha and it makes sense now honestly, she was teasing all this time and I loveeeeeeeeeeee it. 

Okay I made my mind!! many theories are around about Grim Reaper.. and today it made sense, can be the young king?????????????????????????? It could make sense many thiiiiiiiiiiiiiiiiiings ahsdjhasjd

I wonder who Sunny is then.. queen reincarnation?????????? ahhh so many things hahah 
1) How is the queen (?) who was murdered in the first episode, related to the goblin?
I think she and the goblin were in love. They probably got found out by the king and that's why the general was considered a traitor.

2) Why can't Ji Eun-tak see the sword if she is the goblin's bride?
Answer in episode 3.

3) How did he become the goblin?
From what I understood, it's a curse because he killed too many people. My theory is that this curse was given to him by the old lady.

4) Who is the old lady?
Goddess of Birth and probably Life & Love. She might have given "birth" to the Goblin in a way. That might be one of her powers.

5) Can everyone see Grim Reaper?
They explained that people can only see him if he doesn't have his hat. When he puts his hat on, only the deads can see him.

6) why do you think he took it?
With everything that happened, who knows... He might not be human either, he might have enchanted it. That or he has a crush on the goblin's bride.
Here's a couple of crazy theories, just throwing them out there:
A) Old lady in red said "have a look in the mirror" just before he saw the ring. A look in the mirror? So he was the queen then whose ring it was?
Was Sunny then the King? Gender-bender reincarnation :p
B) Old lady in red said something about wanting to punish both Reaper and Sunny. Who'd want to punish those two? Was lady in red perhaps the Queen who'd want to punish them because they were the king (reaper) and the king's advisor (sunny) who was far too encouraging in executing the General and the others, including the Queen in the process?

Probably not, but fun theories nevertheless :D
I am kind of wondering since the queen had that ring, and eun tak mother had the ring and now sunny had her eye on it. Could they somehow be related? 
sometimes i wonder if sunny is the reincarnation of sunny though or eun tak could be a reincarnation of some sort as well. She could see ghosts and things since she shouldn't have been born. 
I wonder if the ring is connected to the sword somehow those are my theories
Unless the queen committed a lot of sins during her life (as explained in ep. 3 on how grim reapers are created), I doubt our grim reaper was the queen. Seems more plausible for Sunny to have been the queen atm.
I have another theory maybe the grim ripper did something so awful like killed someone and it could be sunny past like sunny is reincarnated so that is why he teared up i'm thinking that no idea. If the grim ripper did a sin when he was a alive. omg when will we get to knowww
As @minhsuga said, there is a very low chance that sunny is the king. She could be the queen, though. Didn't she say about the ring "It felt like it belonged on my finger"?
IKR, I wish I could binge-watch it. GR definitely did something bad, since the whole concept of being a GR demands so. But I also think he could be the king.
I also think that Grim Reaper was the king and Sunny was the queen.
The king obviously loved the queen since he had a lot of portraits of her even though she died a long time ago (as seen on episode 3, where Goblin took one of the portraits and the burned the whole place down after) I'm just thinking about what kind of sins the king did to be a grim reaper.

As @nastou19 answered on number 1, I also think that Queen and Goblin were inlove before. First because the king looks hurt looking at them, second because Goblin was about to say something to her but the Queen stopped him saying "I know". I really think siblings doesn't look at each other that way, with such pain and longing. And lastly Goblin said the King was jealous, if they were taking about the throne and such they would have used the word threatened.. but it's all just my crazy theories.

The writer said Goblin was the first fantasy script she ever wrote so she's nervous about it. I think there's no reason to be nervous since here we are, going all krayyyyy with it.
@seventhmonster  The writer has done an epic job so far. Hope it keeps getting better :)
The Queen was Shin's sister, and I think there's a high possibility Sunny is her reincarnated self. She was killed as she was another pillar of Shin's power over the king, that he needed to destroy, in his mad ideas, that Shin wanted his throne.

Also, I think The Grim Reaper is the young king, and being the Reaper is his punishment for jealousy toward and of course murder of Shin and his whole family. Though he doesn't remember his name, on MDL, his name is written as Wang Yeo... Wang (we have come across a lot of dudes with Wang surname this year to ignore that, huh? :D)
Q #1 : there is possibillity that she is her sister or czn bcz that can be the only reason that she got executed with him.. and why did he get executed about that i think king is jealous of him there can be two case
1 if she is sister she must have taken his side as we know that the eunuch was against general 
2 if she is czn he(general) must be her frst loved or the most i think is she must have taken general side bcz she knew that king needs general the most
Q #5 : yes every one can see grim reaper but only when he is without hat ... When he is wearing hat only goblin , heroine , god of birth and other ghostly creature can see him

@UmiAlam I also think the queen is either his relative (sister/ cousin) or his lover... 
Ok, Eun Tak is one of the lost souls Grim reaper is looking for.. Is her mother the second soul he's looking for? She died in 1st episode and he couldn't find her at hospital, so what happened to her soul? Is she a ghost haunting Eun Tak?
I'm also thinking the Grim Reaper is the reincarnation of the king but I had another theory about Sunny. In episode 3, Lee El said that it doesn't matter who will pay for the ring, BOTH of them will pay for the heavy price anyway.  So, if Kim So Hyun's character was the Queen, she was in love with the Goblin and was disloyal to the king?  I don't think Kim So Hyun's character was bad from the past because she was ready to die at that time. Maybe she was a sister of Goblin? Goblin said that Eun Tak was his first and last wife. From his last monologue on episode 4, he said that Eun Tak was his first love.

My funny theory is Sunny was the reincarnation of the evil eunuch manipulating the king at that time. The hole? Why did the Grim Reaper cry? Is it because of the ring or because of Sunny? Maybe as a punishment, everytime he will see Sunny he will be sad, as she in past was the reason why Goblin's family died unfairly.
6) Mmmm I really don't think that the reincarnation of King & Queen are Sunny & Grim Reaper respectively. Mostly because the King didn't seem to care at all when the queen was murdered (for being the goblin's sister?). Grim Reaper & Sunny seemed to know (and loved) each other in another life.
7) What is up with the ring? I have NO idea! That Sunny wanted it so bad, supports the theory of her being the queen, maybe the grim reaper is a former lover of hers? The one who (despite her being the queen) truly loved her; and that was their sin (adultery).
8) Do you really think that Eun Tak can see the sword? I didn't quite buy her explanation on why now she can tell him that she sees it (I think it's merely for plot reasons that se didn't say it before), but yes, she definitely can, otherwise she couldn't have described the lion engravement.