A death yell is a euphemism for the following situation, which happens in fiction a lot and sometimes in real life:
When someone dies and another person is so overcome by grief that he must shout into the air while crying extremely hard, it is known as a "death yell". Sometimes, what is shouted is the name of the deceased; otherwise, it could be some nonsense syllable such as "Aaaaaaaaargh!" Performing one is a way of letting deep emotions out, and could possibly be therapeutic for the performer. Sometimes, the performer is the person who is about to die.
In the Star Trek canon, Klingons do perform a "death yell" when one of them dies. Sometimes, they fight over who gets to do it because Klingon funerals can become elaborate rituals. In Star Trek: The Next Generation, episode "Heart of Glory", Worf kneels and give the death yell when a fellow Klingon dies.[1]
In the TV series Pretty Guardian Sailor Moon, Act 47, Hino Rei performs a "death yell" after finding out that Aino Minako had died, and in Act 49, Tsukino Usagi does one after mercy-killing Chiba Mamoru.[2]Also, in flashbacks, Kunzite performs one after the Earth has been destroyed and the other Shittenou have died.[3]
In one of the final scenes of the 1990 film "The Godfather, Part III", Michael Corleone (actor Al Pacino) gives a death yell at the death of his daughter Mary.[4]