Sure, there's the hit-and-run and murder/ suicide at the end. (Oops. Did we spoil it for you?) But The Great Gatsby is also interested in metaphorical kinds of death: the kind where Gatsby kills the James-Gatz version of himself in order to take a new life, or the kind where the narrator feels himself constantly getting older, or the kind where the various characters' obsession with the past becomes a stand-in for the universal fear of our own mortality. Morbid? Well, when you think about the massive tragedy that was World War I, you can understand why Fitzgerald had death on the mind.
Even though death affects all the characters in The Great Gatsby, only Nick Carraway is willing to confront the reality of death and its meaning for his own life.
In the end, Nick is just as afraid of his own mortality as everyone else is. The story he tells in The Great Gatsby is proof of that.