Jelna
- Appearance: Mammalian; sallow skin, craggy-faced (ENT Novel: Tower of Babel)
- Homeworld: Rigel V
- Major offworld populations: Rigel II
- Four genders: Exomale, exofemale, endomale, endofemale
- Jelna gender based on three-chromosome structure; XY sex-determination plus an additional Z chromosome with 0, 1, or 2 copies
- Zero Z chromosomes result in endo- gender, one or more result in exo- gender