Dramatic Irony in "Hamlet"

We were asked to brainstorm three examples of dramatic irony in Hamlet.

What is the definition of dramatic irony, anyway? Dramatic Irony is: "irony that is inherent in speeches or a situation of a drama and is understood by the audience but not grasped by the characters in the play." (Google definition)

1. There is dramatic irony when the ghost tells Hamlet that he was poisoned by Claudius. No one else in the play knows this has happened, so the audience is the only one(s) who understand why Hamlet is going to act crazy.

 2.. There is the presence of dramatic irony where Hamlet tells Horatio and Marcellus  that he is going to pretend to act mad. This is an example of dramatic irony because the only people who know that Hamlet is "acting" is Horatio, Marcellus and the audience.

3. Another example of dramatic irony in Hamlet is when Hamlet rejects (dumps, ends his relationship)  Ophelia. Hamlet does not realize how madly in love Ophelia is with him. The audience is the only one who knows, as it can be shown when Ophelia begins to act crazy. Hamlet thinks nothing of it, but the audience understands why Ophelia is acting this way. Therefore being dramatic irony as Hamlet does not know that the girl he rejected is madly in love with him.