" You're The One " Cast : Ashley Benson as Lindsey Hilton Niall Horan as Niall Horan Nathan Fillion as Richard Hilton Stana Katic as Kate Brown ( Kate Hilton ) Gregg Sulkin as Mason Greybeck Emma Watson as Gabriella Brown ( Gabriella Hilton ) Harry Styles as Harry Styles Lucy Hale as Amy Clarkson Liam Payne as Liam Payne Gigi Hadid as Gigi Hadid Zayn Malik as Zayn Malik Eleanor Calder as Eleanor Calder Louis Tomlinson as Louis Tomlinson