They were killed by Macbeth because he blamed them for Duncan's murder.
"I" said Macbeth, "with the servants' daggers. I killed Macbeth."
And then Macbeth asked Macbeth if he confronted Macbeth on killing Macbeth with Macbeth.
In shakesperes story it is said that Macbeth killed him in his sleep but in reality historians believe he was killed (by Macbeth) during or shortly after the battle.
Macbeth kills Duncan in his own castle at night time.
He had his suspicions because the fact the Macbeth killed the servants he blamed the murder on.
Macbeth said that he killed Duncan's grooms out of anger over Duncan's death.
Macbeth was not a vassal of King Duncan. Macbeth's act of killing King Duncan would be considered regicide because he unlawfully killed his king, who was his sovereign and ruler.
The title character, Macbeth, Thane of Cawdor.
Yes, Macbeth is overcome with guilt and remorse after he kills Duncan. He is haunted by his actions and struggles to come to terms with what he has done.
Malcolm (Duncan's son) did not kill Macbeth, it was Macduff (Thane of Fife).
Nobody was. That's the point. Macbeth killed a good man.