Millennium Trilogy by Stieg Larsson. I usually don't read this type of book but I read "The Girl With the Dragon Tattoo" because of all the talk about it and was instantly hooked. Too bad he only wrote these 3 before he passed away.
The Hunger Games Trilogy Boxed Set - - The extraordinary, ground breaking New York Times bestsellers The Hunger Games and Catching Fire, along with the third book in The Hunger Games trilogy by Suzanne Collins, Mocking
Fifty Shades Trilogy: Fifty Shades of Grey, Fifty Shades Darker, Fifty Shades Freed Boxed Set - Now available as a three-volume paperback boxed set, E L James’s New York Times bestselling trilogy has been hailed by Entertainment Weekly