In "The Cask of Amontillado," does Montresor feel guilty about killing Fortunato?

In Gothic narratives such as Poe's "A Cask of Amontillado," the narrator has the "privilege of irrationality and passion over rationality and reason" (enotes).  That being stated, it is, indeed, questionable that Montesor feels any guilt whatsoever over his murder of Fortunato.  That this murder is premeditated is apparent from the beginning of the story as Montesor mentions that he has borne "a thousand injuries," but now has finally vowed revenge and has a singleness of purpose, so typical of Poe's narrators.

Like a cat who toys with his victim before finally killing it, Montesor leads the unwitting Fortunato through narrow, damp openings in the catacombs, parodying him with mock gestures of a mason as he puns on the word itself, feigning concern for his welfare, only to take him farther until finally tethering his unsuspecting victim to a wall.  When Fortunato screams, Montesor hesitates as a cat hesitates to see so much life left in his victim.  He pulls his sword, not out of any guilt, but to reassure himself that there is no escape for Fortunato. 

In the final paragraph the irrational narrator wishes to still hear agony in his victim.  He "thrusts a torch through the remaining aperture," but a "jingling of bells" is the only response.  "My heart grew sick--on account of the dampness of the catacombs," Montesor says, and he hastens to make an end of his work.  Like the cat who is disappointed that his prey is now limp and no more fun to torture, he leaves the scene.  Certainly there is no guilt in the narrator's subsequent remark, proudly and mockingly said, 

JFor the half of a century no mortal has disturbed them.  In pace requiescat! 

In "The Cask of Amontillado," does Montresor feel guilty about killing Fortunato?

Throughout most of his evil deed against Fortunado, Montresor does not demonstrate any sense of guilt or regret.  In fact, he seems to be rather enjoying himself and his diabolical plan.  He teases Fortunado along, goading him and very cleverly manipulating the man to go further and further into the catacombs.  At one point, when Fortunado is screaming and struggling with the chains, Montresor states,

"The noise lasted for several minutes, during which, that I might hearken to it with the more satisfaction, I ceased my labours and sat down upon the bones."

So not only is he enjoying the screaming, but he sits down to relish it even more.

There is one point however, that Montresor shows a bit of hesitancy.  Guilt?  Not sure, but hesitancy for certain.  Fortunado picks up the pace of his screaming, and Montresor writes,

"For a brief moment I hesitated, I trembled. Unsheathing my rapier, I began to grope with it about the recess"

So, he is a bit worried and startled; he sticks his sword in to try to determine if Fortunado is still standing, or get a sense for what is going on.  He hesitates in his plan.  However, his hesitation lasted for merely "an instant" before he resumed his work with great satisfaction.

The best indication of guilt is at the end.  Fortunado has stopped making noises, and is silent.  Montresor writes, "My heart grew sick".  The thought of Fortunado dying in there, for a moment, makes him sick.  However, he blames it on "the dampness of the catacombs" and hurries away.  So, his sick heart does make him feel bad probably, but in denial, he blames it on something else and rushed away.  The fact that he is confessing his story at a later date might also indicate that he has felt guilty for it, because he is unburdening himself of the tale.

I hope those thoughts help; good luck!

Does Montresor regret killing Fortunato in The Cask of Amontillado?

In burying Fortunato alive, Montresor was also burying the poisonous feelings he harbored toward the man who'd insulted him in a "thousand" different ways. That being the case, it's hard to believe that Montresor feels any regret over his actions. When he confesses his heinous crime, Montresor seems quite pleased with himself, not just for having murdered Fortunato but for having gotten away with it for so long. This is hardly an expression of regret.

The fact that Montresor is confessing his crime could be taken as a sign of guilt, but that's not quite the same thing as regret. In any case, an equally plausible case could be made for saying that Montresor's confession is less to do with unburdening a guilty soul than it is a simple act of bragging to someone else—a spiritual confessor like a priest, perhaps—about what he'd done.

Indeed, Montresor seems to have felt an overwhelming sense of freedom ever since he killed Fortunato: a weird sense of calm, inner peace, and contentment brought about by the removal of the source of so much inner torment. It would be hard to conclude, then, that Montresor regrets having carried out his act of brutal revenge given how much peace of mind it's brought him.

What evidence suggests that Montresor regrets killing Fortunato in Poe's "The Cask of Amontillado"?

I do not believe that Montresor ever regretted his decision to kill Fortunato. In the first paragraph of The Cask of Amontillado, Montresor says that he had vowed revenge upon Fortunato after Fortunato insulted him; he says that he was definitely going to get his revenge because he needed to "punish with impunity" Fortunato for the wrong he had committed. Of course, walling someone into a small alcove and letting them die slowly of starvation and dehydration is a bit extreme, but he certainly ensured that Fortunato would never insult him again.

That being said, there is one line at the end of the story that could be construed as showing a sign of guilt in Montresor.

My heart grew sick—on account of the dampness of the catacombs.

His sick heart could be seen as being sick with guilt, and he is simply blaming it on the dampness of the catacombs to avoid the fact that he actually feels guilty for his revenge. But considering the tone of the rest of the story, I doubt that that is the case.

As for relating it to Poe's life, it is possible that you could connect it to the story with the theme "no regret." Montresor does not regret killing Fortunato, and Poe did not regret either one thing he did or multiple or even all of them. That is entirely conjecture, my own opinion, and it is very weak at that, considering the (often self-inflicted) hardships Poe faced in his life. To form your own opinion, I have provided a link that tells the story of Poe's life.

In "The Cask of Amontillado," does the narrator feel guilty for his actions later?

There is some evidence that Montresor felt a small amount of remorse after he killed Fortunato.

Montresor is not a mentally stable man.  We can tell this because we know that Fortunato insulted him in some minor way that was so insignificant that Fortunato himself was not aware of it (or he never would have gone into the catacombs with him at night, letting his guard down), and yet he still wants to kill him.  Montresor is a murderer.  He wants to kill this man, and plans a cold-blooded murderer in such a way that he can get away with it.  This is of utmost importance to him.  If he doesn’t get away with the murder, he will not have gotten his revenge.

At first, we know that Montresor has felt no remorse.  He seems to luxuriate in the murder, stopping several times to enjoy Fortunato’s suffering.

… I heard the furious vibrations of the chain. The noise lasted for several minutes, during which, that I might hearken to it with the more satisfaction, I ceased my labours and sat down upon the bones.

It certainly seems as if he is enjoying the fact that his victim is frightened out of his mind.  He stops to enjoy it.  He waits it out, sitting on a pile of bones.  It definitely seems to be the work of a disturbed, demented, remorseless, despicable mind.

However, if you look closely, you will also notice something else.  You will notice that Montresor is not as self-assured as he seems.  He seems confident.  He has planned every detail.  He has everything prepared, he convinces Fortunato to come down, and he uses reverse psychology beautifully.  He seems every bit the megalomaniac.  Yet while he talks about his family crest, says he is a connoisseur of wine, and pretends to be a Mason, it is clear that he not the member of that secret society.  This calls into question the other things too.  Perhaps he is just a pretender, and not as self-confident as he pretends to be.

Notice that after his play of strength, sitting on the bones, the shrill of the screams causes him to thrust “violently back” and even tremble.  That could definitely be a sign of remorse.

However, the greatest indication that Montresor actually does have some remorse is what he says himself, when he finally realizes that he has killed a man.

No answer still. I thrust a torch through the remaining aperture and let it fall within. There came forth in return only a jingling of the bells. My heart grew sick; it was the dampness of the catacombs that made it so.

He dismisses the idea of remorse, but that does not mean he did not feel it.  He wants to be this cold, hard, murderer.  He wants to get revenge.  Yet at the same time, he did feel sick.  He dismisses it as the dampness, but it wasn’t.  It was regret.  It was the realization that he did kill someone.  It was remorse, plain and simple.  It might have been a tiny bit of barely acknowledged remorse, but it was remorse nonetheless.