| 100th Training Division (Leader Development) | airborne infantry division, United States Army infantry division, training division | Fort Knox | 1918 |
| 20th Century Studios | television production company, production company, film production company, film studio | Fox Plaza, Walt Disney Studios | 1985 |
| 20th Century Studios Home Entertainment | production company, business | Century City, Los Angeles | 1976 |
| 20th Television Animation | business | Los Angeles | May 19, 1999 |
| 21 Club | restaurant | — | 1922 |
| 2K Sports | video game publisher | Novato | January 25, 2005 |
| 3 Arts Entertainment | production company | Beverly Hills | 1991 |
| 3D Realms | video game developer | Garland | 1994 |
| 3D Systems | business, public company | Rock Hill | 1986 |
| 3dfx Interactive | business, enterprise | San Jose | 1994 |
| 3M | business, conglomerate, public company | Maplewood | 1902 |
| 4Licensing Corporation | television production company, public company | New York City | 1970 |
| 7-Eleven | brand, business, gas station chain, convenience store chain | Dallas, Irving | 1927 |
| 87North Productions | film production company | Santa Monica | April 1, 2019 |