The name Leon is mentioned only in environmental storytelling in The Last of Us Part II, and it references another character.

That was not a trick of the light, Josh Peck did in fact have a quick cameo in “The Last of Us.” ...

This week on 'The Last of Us' Ellie and Dina dodge infected and Seraphites, and Ellie confronts Nora — and brand-new dangers — in the hospital.