1. 1977 James Taylor song that references Albert Einstein: "Secret O'Life"
2. Lead singer of the Cranberries: Dolores O'Riordan
3. His biggest hit was "Alone Again, Naturally" in 1972: Gilbert O'Sullivan
4. It's Boy George's real name: George O'Dowd
5. Red-haired mandolinist who sang and played with Hot Rize and last year toured with Mark Knopfler: Tim O'Brien
6. Blind Irish harper and composer of the 18th century: Turlough O'Carolan
7. The oldest of six brothers, his group has hit the Top 40 in the 60s, 70s, 80s, 90s, and 2000s - we're still waiting on the 2010s: O'Kelly Isley
8. "Don't cry, don't raise your eye, it's only teenage wasteland...": "Baba O'Riley"
9. Fiddler and guitarist who recorded Appalachia Waltz with Yo-Yo Ma and Edgar Meyer: Mark O'Connor
10. He sang with Gene Kelly and Debbie Reynolds in Singin' in the Rain: Donald O'Connor
11. Ohio soul group whose hits included "Love Train" and "Back Stabbers": The O'Jays
12. Singer/songwriter who hit Number One in 1977 with "Undercover Angel": Alan O'Day
13. Rapper/basketball player who was probably fated to end up on the Boston Celtics: Shaquille O'Neal
14. Former De Dannan singer who has worked with such musicians as Jerry Douglas, Bela Fleck, and Alison Krauss: Maura O'Connell
15. A 2003 Number One country hit for Alan Jackson and Jimmy Buffett: "It's Five O'Clock Somewhere"
16. "Nothing Compares 2 U" singer: Sinead O'Connor
17. He had a hit duet with Cherelle, "Saturday Love," in 1985: Alexander O'Neal

Bonus: New Orleans musician and former proprietor of the Irish Channel Pub (RIP): Danny O'Flaherty