In Act 2, the plot stops while actors put on a play (and it repeatedly stops as unexpected events unfold). And in Act 5 Laertes provides a uniquely grieving character that helps Hamlet let go of his guilt.
"I shall despair. There is no creature loves me;/And if I die, no soul shall pity me:/Nay, wherefore should they, since that I myself/Find in myself no pity to myself?