Here's an overview of every version of macOS and Mac OS X Apple has released. You'll find a complete list of OS X version code names, along with internal code names (if available):

1. OS X 10 beta: Kodiak - 13 September 2000
2. OS X 10.0: Cheetah - 24 March 2001
3. OS X 10.1: Puma - 25 September 2001
4. OS X 10.2: Jaguar - 24 August 2002
5. OS X 10.3 Panther (Pinot) - 24 October 2003
6. OS X 10.4 Tiger (Merlot) - 29 April 2005
7. [OS X 10.4.4 Tiger (Chardonnay)]
8. OS X 10.5 Leopard (Chablis) - 26 October 2007
9. OS X 10.6 Snow Leopard - 28 August 2009
10. OS X 10.7 Lion (Barolo) - 20 July 2011
11. OS X 10.8 Mountain Lion (Zinfandel) - 25 July 2012
12. OS X 10.9 Mavericks (Cabernet) - 22 October 2013
13. OS X 10.10: Yosemite (Syrah) - 16 October 2014
14. OS X 10.11: El Capitan (Gala) - 30 September 2015
15. macOS 10.12: Sierra (Fuji) - 20 September 2016
16. macOS 10.13: High Sierra (Lobo) - 25 September 2017
17. macOS 10.14: Mojave (Liberty) - 24 September 2018
18. macOS 10.15: Catalina (Jazz) - 7 October 2019
19. macOS 11: Big Sur - 12 November 2020
20. macOS 12: Monterey - 25 October 2021