This question, actually is one that is very much debated in regards to this play. In order to answer it satisfactorily, you must define "to blame." Do you mean who actually wielded the knife? No question, then, it's Macbeth himself. Though we don't see the murder onstage, he and Lady Macbeth have a scene -- Act II, scene ii -- in which Macbeth has just come from the murder.
However, "blame" is often distributed, in a murder, to those who function as accessories to the crime. In this case, is Lady Macbeth also "to blame?" How about The Witches? Let's look at both of these possibilities individually.
First, Lady Macbeth, in the scenes before the murder, seems to drive the action forward. In Act I, scene v, she all but declares the murder a done deal. She says that "never/[s]hall sun that morrow see," referring to Duncan's staying the night at their home, but not living to see the next day. She ends this discussion with a reluctant Macbeth by saying, "Leave all the rest to me," implying that she will see that the murder is committed. And the actual plan, divulged in Act I, scene vii, is given to Macbeth by Lady Macbeth. She says:
. . .When Duncan is asleep
. . .his two chamberlains
Will I with wine and wassail so convince
That memory. . .
Shall be a fume. . .when in swinish sleep
Their drenched natures lie as in a death,
What cannot you and I perform upon
The unguarded Duncan?
This plan implicates Lady Macbeth as being the mastermind behind Duncan's death, and, as such, partly to blame for the murder.
The Witches are also considered by some to share in the blame, since their prediction of Macbeth's becoming King is what leads him first to consider the idea. Have they poisoned his brain in some way, created some evil spell that has caused him to act against his better nature in killing Duncan? Well, this can only be a supposition, there is not evidence in the text to prove it. But it is certainly worth considering that the Witches, through their supernatural intervention, also share some of the blame for Duncan's death.
So, Macbeth is the actual murderer in the play, but Lady Macbeth and the Witches could both be considered to share in the blame for the death of Duncan.
The links below will give more detail for considering this question further.
To try to blame anybody for the death of Duncan is to simplify the moral-psychological web of Shakespeare's play. The murder of Duncan is the culmination of a number of complex initiatives.
First, consider the role of the witches. The witches represent the supernatural world of evil, and they choose to equivocate to the tragic undoing of the brightest of all men in Scotland. They are sure to blame for the killing of Duncan. The witches catalyze the dormant ambition in Macbeth to expedite the murder of the good old king.
Second, consider the , 'vaulting ambition' in Macbeth. This ambition lies at the root of Duncan's death. 'Fair' Macbeth, so admired and rewarded by Duncan, is won over the 'Foul' Macbeth. But for his ambition, the 'supernatural soliciting' could not have been operative.
Third, you must consider the role of Lady Macbeth. She has been accused of having played the role of the 'fourth witch'. She apostrophizes the forces of darkness to assume the direst cruelty to stand by the ambition of her husband. But for her active intervention, encouragement and support, Macbeth could not have killed Duncan.
Fourth, should we not say that Duncan's essential goodness and simplicity are also to blame? Duncan is too good to secure himself against treachery and conspiracy.
It depends, there are 2 sides I'm gonna 1st explain the side for the people that believe that macbeth is the one to blame.MacBeth could have explained to his wife that her idea was crazy and it was a prophecy It was going to come true anyway.Macbeth also could have stopped the at the last minute and realize what he was about to do was crazy-Killing is never the answer.
-Lady MacBeth-Lady MacBeth had prayed for the gods or god to unsex her which means to make her more man which means more agressive.Lady Macbeth did convince MacBeth to kill King Duncan.However as I have stated in my other paragrah about MacBeth that he did have the the chance not to kill King Duncan.Although Lady MacBeth did have a part in the murder twice.
1st she had hid the knife and gotten blood on her hands to which means she had part in the murder part 2nd is when people had discovered that King Duncan died MacBeth was looking pretty nervous no one had noticed yet but they soon would.In order to not get caught Lady MacBeth had fainted so all the attention would turn to her so MacBeth had the chance to get himself together
i personally think behind the death of Duncan the most important part was the role of witches and their prophecy in the play"MACBETH".After this we can say that the character Macbeth is there.the role of witches is very noying part in the play that how he describe their prophecies that in favoure of macbeth they said that you are now thane of cawdor and glamis and again they says that you will be the next king of scotland ,in account of banko they prophesied that you will not be the king but you will b the fater of king.that provokes the a mind game in the mind of macbeth and he cumitted a very cruel type of muder of the present king Duncan.so i think behind this there are very importat role of witches.
Macbeth is the one to be blamed for the killing of Duncan. However, he is influenced by his wife's goading to perform the killing because Lady Macbeth rebuked his manhood. So, in order to prove that he is 'a man', he perform the killing by himself. Only then right after he performed the killing, Lady Macbeth took the daggers and smear the blood on the guards; to prove that they are the ones who had killed Duncan.
Macbeth is the mastermind ehind duncan's death