Preheat oven to 350°F (175°C).
In a mixing bowl, combine graham cracker crumbs, sugar, and melted butter. Press mixture firmly into the bottom of a 9-inch pie pan to form the crust.
Bake the crust for 8 minutes, then allow it to cool completely.
In a large bowl, beat the cream cheese until smooth.
Add mashed avocado, sweetened condensed milk, lime juice, and lime zest. Blend until creamy.
Gently fold in the whipped topping until fully incorporated.
Pour the filling into the cooled crust and smooth the top.
Refrigerate for at least 4 hours, or until set.
Serve chilled, optionally garnished with lime slices or extra zest.