Arcus may mean:
- Arcus AS, a Norwegian producer of liquor
- Arcus cloud, a low, horizontal cloud formation
- Arcus Foundation, a global foundation advancing social justice conservation issues
- Arcus II: Silent Symphony and Arcus Odyssey, computer games
- Arcus (Titan) (pl. arcūs), any arc-shaped feature found on Saturn's moon Titan (planetary geology)
- Arcus senilis, a faint whitish ring around the iris in elderly people; discolouration of the iris with age
- Schempp-Hirth Arcus a two-seat glider
- Arcus functions are the Inverse trigonometric functions.