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