SM4, Sm4, sM4 or sm4 stands for:
- Spider-Man 4, a cancelled Spider-Man film
- Superman 4, the fourth Superman film
- Scary Movie 4, the fourth Scary Movie film
- VR Class Sm4, a type of train operated by the VR Group
- SM4 postcode area, the Sutton postcode area covering Morden, Morden Park, Lower Morden and St. Helier.
- STS-125 (Servicing Mission 4), the final servicing mission to the Hubble Space Telescope