Related Clues:

• Unparalleled
• Curiosity
• Unrivaled
• One of a kind
• Short-lived success
• Rarer than rare
• Individual
• Blue moon, e.g.
• Sole
• Hen's tooth, e.g.
• Without equal
• Peerless
• Singular
• Matchless
• One who had 15 minutes of fame, perhaps