Olivia Newton-John - Magic: The Very Best Of Olivia Newton-John (2001)

UTV Records' Magic: The Very Best of Olivia Newton-John is the best compilation ever assembled on Newton-John's career, largely because it does cover her entire career, hitting every major point from her early-'70s soft country-pop hits, like "I Honestly Love You," through her star-making turn in Grease, selections from Xanadu, up to the Physical era and its fallout. That takes a total of 20 tracks, plus the bonus track of "The Grease Megamix," and that gives a listener nearly everything they need from Olivia. When the biggest complaint is that the collection sequences "You're the One That I Want" before "Summer Nights," it means that this is certainly a collection that can be called definitive.