迷你海王星（Mini-Neptune）又称气态矮星或过渡行星，是指實際質量低於太陽系的天王星和海王星，但卻和海王星相當類似的太陽系外行星。而這樣的行星大氣層上層會有由氫和氦組成的厚層，在之下是極深的水和氨等分子較大的揮發物。如果沒有厚大氣層的話，這類行星則是海洋行星[1]。
在迷你海王星和組成成分以岩石為主的超級地球之間可能有一個分界，而這個界線可能是二倍地球半徑。位于宜居带的系外行星开普勒22b与格利泽581d都是迷你海王星[2][3]。
Optical to near-infrared transit observations of super-Earth GJ1214b: water-world or mini-Neptune? （页面存档备份，存于互联网档案馆）,
E.J.W. de Mooij (1), M. Brogi (1), R.J. de Kok (2), J. Koppenhoefer (3,4), S.V. Nefs (1), I.A.G. Snellen (1), J. Greiner (4), J. Hanse (1), R.C. Heinsbroek (1), C.H. Lee (3), P.P. van der Werf (1), Architecture of Kepler's Multi-transiting Systems: II. New investigations with twice as many candidates （页面存档备份，存于互联网档案馆）, Daniel C. Fabrycky, Jack J. Lissauer, Darin Ragozzine, Jason F. Rowe, Eric Agol, Thomas Barclay, Natalie Batalha, William Borucki, David R. Ciardi, Eric B. Ford, John C. Geary, Matthew J. Holman, Jon M. Jenkins, Jie Li, Robert C. Morehead, Avi Shporer, Jeffrey C. Smith, Jason H. Steffen, Martin Still
- Six New Planets: Mini-Neptunes Found Around Sunlike Star （页面存档备份，存于互联网档案馆）, Victoria Jaggard, National Geographic News, Published February 2, 2011
- Barnes, Rory; Jackson, Brian; Raymond, Sean N.; West, Andrew A.; Greenberg, Richard. The HD 40307 Planetary System: Super-Earths or Mini-Neptunes?. The Astrophysical Journal. January 13, 2009, 695 (2): 1006. Bibcode:2009ApJ...695.1006B. arXiv:0901.1698
. doi:10.1088/0004-637X/695/2/1006.
