Joannis
- Alternate forms for the name John
- Andreas Eudaemon-Joannis
- Giovanni Giorgi (composer)
- Giovanni Maria Alemanni
- Ioannis
- Iohannis
- Jan Weenix
- Jan z Lublina
- Jens Nilssøn
- Joanni Perronet
- Joannis Andreou
- Joannis Antonius de Sancto Giorgio
- Joannis Avramidis
- Joannis Capodistrias
- Joannis Eschuid
- Joannis Melissanidis
- Joannis Metaxas
- Joannis Phrangoudis
- Joannis Romberch de Kyrspe
- Joannis Vislicensis
- Joannis de Segovia
- Johann Hedwig
- Johannis (disambiguation)
- John Martyn (botanist)
- Joseph de Joannis