When Fantastic Beasts & Where To Find Them came out in 2016, it was notable Rowling started killing characters off by the end of the first film. Credence Barebone was dead, for instance, as was his adopted mother, Mary Lou, and Percival Graves. Jacob wasn't dead, but his memory, including his love for Queenie, was erased. This was a somewhat unhappy ending in direct contrast to the Potter films. But when Crimes of Grindelwald arrived, Rowling had undone both Credence's death and Jacob's memory loss. This leads fans to ask, will Leta Lestrange be in Fantastic Beasts 3? Warning: Spoilers for Fantastic Beasts: The Crimes of Grindelwald follow.
Once again, Rowling gave her Fantastic Beasts story something of a downer of an ending. Queenie leaves Jacob behind and joins Grindelwald. Credence abandons Nagini to follow Grindelwald in a search for answers to who he is. But the biggest downer was the discovery Leta Lestrange, one of the few witches of color to have a leading role in a wizarding world story, sacrifices herself to Grindelwald.
Nominally, she does it so her fiancé Theseus and her best friend Newt can both escape and fight another day. But her death is really in service of the character growth of the male lead, as Newt stops trying to use his wizarding privilege to beg off the fight, and accepts he too must stand against evil as the Ministry has been asking him to for a year.
Chances are, in this case, Leta's death will really stick. Unlike Credence, where Rowling still had character reveals to do, Leta's full mystery was laid out before audiences in the current film. She was bullied and scored by her peers at Hogwarts, due to her parentage and her father's apparent scorn for her. She fell in love with Newt because he was kind to her. She chose to marry Theseus because he had his life together and Newt didn't.
Most importantly, Leta's childhood secret was revealed. She killed her baby half-brother, Corvus. It wasn't strictly her fault. She was a child, her decision to switch her baby brother with another non-crying baby is little kid logic at it's finest. It's not her fault the boat started to sink before she could switch them back or tell anyone what she had done. Nor is it her fault the lifeboat carrying her real brother capsized before her eyes. Juries would probably convict her of involuntary manslaughter, and she would get off with time served.
But when Rowling has a character run their course like this and uses their death to teach the hero a life lesson — think Cedric Diggory and Dobby — it's a sign she's done with the character, and their demise will stick. Chances are, Leta Lestrange will not return in Fantastic Beasts 3, other than as a ghost.