Why is Hamlet called a great tragedy?
My initial reaction is that you will find many different answers to this question. From my own point of view, I think one reason why Hamlet can be considered a tragedy is that there is little in terms of happy ending present. Everyone dies, either at their own hand or at someone else's. There is little in way of redemption offered to the characters. Those who might have been happy at the start of the play end up suffering in misery by the end and those who were unfortunate at the start end up acquiring more pain and suffering. The reader themselves can only feel some level of solace in making a commitment to not live their own lives like the characters in the work. I would say that part of the tragedy inherent is that characters' greatest strength result in their own downfall. Hamlet's ability to perceive and deduce is what ends up preventing him from taking action and causes him even more agony. Ophelia's trust and sensitivity towards others does not afford her a buffer or distance from the manipulation of others and Hamlet's cruelty. In these lights, I would see the play as one of great or intense tragedy.
"Hamlet" is a great tragedy because nothing seems to be positive in the story. Hamlet is well written and is a conflicting character. He changes moods often, speaks to himself in different manners indicative of his anger, depression, and moods. The story involves murder and betrayal. The story begins with the murder of his father and his father’s ghost calling out for revenge. Though Hamlet may be a hero to some, he has no friends. Hamlet does not have a good relationship with women. Hamlet rejects Ophelia and after her father's death, Ophelia takes her own life. The story is one of revenge and deep thought and emotion. Revenge only leads to many deaths of the father's and sons in the book. There is no one in the story who actually finds any happiness. Therefore, "Hamlet" is a tragedy.