Janssen
Janssen may refer to:
Astronomy
- Janssen (lunar crater)
- Janssen (Martian crater)
- Janssen (planet), an exoplanet also known as 55 Cancri e
Other
- Janssen (surname) is a common Dutch surname, cognate of "Johnson"
- Janssen Biotech, American biotechnology company
- Janssen COVID-19 vaccine, a COVID-19 vaccine
- Janssen Pharmaceuticals, a Belgian company
- USS Janssen (DE-396), World War II US Navy destroyer escort
- E. Janssen Building, a historic building in Eureka, California