| 83 Leonis Bb | |
| Discoverer: | Marcy, Butler, Vogt et al. |
| Discovery Site: | United States |
| Discovered: | 25 January 2005 |
| Discovery Method: | Doppler spectroscopy |
| Apsis: | astron |
| Semimajor: | 0.12186± |
| Eccentricity: | 0.13 ± 0.07 |
| Period: | 17.054 ± 0.003 d |
| Time Periastron: | 2,450,449 ± 2 |
| Arg Peri: | 196 ± 32 |
| Semi-Amplitude: | 7.9 ± 0.6 |
| Star: | 83 Leonis B |
83 Leonis Bb, also catalogued as HD 99492 b or abbreviated 83 Leo Bb, is an extrasolar planet with a minimum mass of 1.5 Neptune mass. It is located approximately 59 light-years away in the constellation of Leo (the Lion). The planet was discovered in January 2005 by the California and Carnegie Planet Search team, who use the Doppler spectroscopy method to detect planets. It orbits in a close orbit around the star, completing one orbit in about 17 days. The HARPS-N spectrograph discovered a second Neptune-like exoplanet in 2022 orbiting at 95 days.