Olivia Newton-John traversed a lot of musical ground across her storied career—and that, of course, included Christmas albums, of which she recorded a few over the years. This set of favorites isn’t just a holiday celebration, but also a showcase for the Australian pop icon’s timeless voice and stylistic range, whether she’s bringing an elegant touch to classics (“O Come, All Ye Faithful”) and originals (“A Mother’s Christmas Wish”) or duetting on fun, jaunty numbers with John Farnham (“Here Comes Santa Claus”) or her Grease co-star John Travolta (“Rockin’ Around the Christmas Tree”).