What does the ghost say about Gertrude?

The ghost tells Hamlet to avenge King Hamlet’s murder by killing Claudius, while sparing Gertrude from revenge.

The ghost presents Claudius as the true villain: the man who poisoned King Hamlet, stole the crown, and corrupted the marriage bed. It says that “the serpent that did sting thy father’s life now wears his crown,” identifying Claudius as the murderer behind the false story that King Hamlet died from a snakebite. The ghost also condemns Claudius for turning Denmark’s throne into “a couch for luxury and damnèd incest,” linking Claudius’s crime to his marriage with Gertrude.

About Gertrude herself, the ghost warns Hamlet against taking action against her: “howsoever thou pursues this act, / Taint not thy mind, nor let thy soul contrive / Against thy mother aught.” In other words, Hamlet should pursue revenge, yet he must not plot harm against his mother or let hatred of her corrupt him. Later, when the ghost appears again in Gertrude’s room, it reminds Hamlet to keep focused on vengeance against Claudius and urges him not to let Gertrude suffer.

This matters because Hamlet’s disgust with Gertrude becomes one of his deepest obsessions. The ghost’s warning creates a tension Hamlet never handles cleanly: he is commanded to punish murder, yet he is also told to restrain his anger toward the woman whose remarriage feels to him like a betrayal.