The abbreviations M23 and M 23 denote, among other things:
- an open star cluster in the constellation Sagittarius, see Messier 23 ;
- a computer program for software distribution and system administration, see M23 (Software) ;
- a metric thread ;
- a sporadic group in the mathematical field of group theory .
- an aircraft from the aircraft manufacturer BFW (Bayerische Flugzeug Werke), Augsburg, see Messerschmitt M23
- Movement March 23 is a rebel group in the Democratic Republic of the Congo
- Motorways and trunk roads