H
- Ernst Haeckel (1834–1919), German physician, zoologist and evolutionist
- Hermann August Hagen (1817–1893), German entomologist
- J. B. S. Haldane (1892–1964), British evolutionary biologist and co-founder of population genetics
- William Donald Hamilton (1936–2000), British evolutionary biologist
- Sylvanus Charles Thorp Hanley (1819–1899), British conchologist and malacologist
- Thomas Hardwicke (1755–1835), English naturalist
- Alister Clavering Hardy (1896–1985), English marine biologist and pioneer student of the biological basis of religion
- Richard Harlan (1796–1843), American naturalist, zoologist, physicist and paleontologist
- Denham Harman (born 1916), American biogerontologist, father of the free radical theory of aging
- Maarten 't Hart (born 1944), Dutch biologist and writer
- Ernst Hartert (1859–1933), German ornithologist
- Gustav Hartlaub (1814–1900), German zoologist
- Karl Theodor Hartweg (1812–1871), German botanist
- William Henry Harvey (1811–1866), Irish phycologist
- Hans Hass (born 1919), Austrian biologist
- Frederik Hasselquist (1722–1752), Swedish naturalist
- Arthur Hay, 9th Marquess of Tweeddale (1824–1878), English ornithologist
- James Hector (1834–1907), Scottish geologist, naturalist, and surgeon
- Charles Hedley (1862–1926), naturalist, active in Australia
- Oskar Heinroth (1871–1945), German biologist, a founder of ethology
- Wilhelm Hemprich (1796–1825), German naturalist
- Willi Hennig (1913–1976) German biologist, founder of cladistics
- John Stevens Henslow (1796–1861), English mineralogist, botanist and clergyman
- Johann Hermann (1738–1800), French physician and naturalist
- Albert William Herre (1868–1962), American ichthyologist and lichenologist
- Alfred Hershey (1908–1997), American bacteriologist, winner of the 1969 Nobel Prize in Physiology or Medicine for his work on the genetics of viruses
- Philip Hershkovitz (1909–1997), American mammalogist noted especially as a primatologist
- Leo George Hertlein (1898–1972), American paleontologist and malacologist
- Archibald Vivian Hill (1886–1977), British physiologist, winner of the 1922 Nobel Prize in Physiology or Medicine for elucidation of mechanical work in muscles
- Brian Houghton Hodgson (1800–1894), English naturalist
- Bruno Hofer (1861–1916), German fisheries scientist
- Johann Centurius Hoffmannsegg (1766–1849), German botanist, entomologist and ornithologist
- Jacques Bernard Hombron (1798–1852), French naturalist
- Leroy Hood (born 1939), American biochemist, developed high speed automated DNA sequencer
- Robert Hooke (1635–1703), British natural philosopher and Secretary to the Royal Society
- Joseph Dalton Hooker (1817–1911), British botanist, explorer and Director of Kew Botanic Gardens
- William Jackson Hooker (1785–1865), British botanist, Director of Kew Botanic Gardens
- John "Jack" Horner (born 1946), American paleontologist, specialized in dinosaurs
- Thomas Horsfield (1773–1859), American naturalist
- Bernardo Houssay (1887–1971), Argentine physiologist, winner of the 1947 Nobel Prize in Physiology or Medicine for the function of the pituitary hormones in regulating blood sugar (glucose) in animals.
- Martinus Houttuyn (1720–1798), Dutch naturalist
- Albert Howard (1873–1947), British botanist
- Eliot Howard (1873–1940), English ornithologist
- Sarah Blaffer Hrdy (born 1946), U.S. anthropologist who made contributions to evolutionary psychology and sociobiology
- David H. Hubel (born 1926), Canadian-Born American neurobiologist, winner of the 1981 Nobel Prize in Physiology or Medicine for research on the visual system
- François Huber (1750–1831), Swiss naturalist
- Ambrosius Hubrecht (1853–1915), Dutch zoologist
- William Henry Hudson (1841–1922), Argentinian-British ornithologist
- Alexander von Humboldt (1769–1859), German naturalist and explorer
- Allan Octavian Hume (1829–1912), British ornithologist
- Rob Hume, British ornithologist
- George Evelyn Hutchinson (1903–1991), American ecologist and limnologist
- Frederick Wollaston Hutton (1835–1905), English biologist and geologist, later worked in New Zealand
- Julian Sorell Huxley (1887–1975), English zoologist and contributor to the modern evolutionary synthesis; first D-G of UNESCO
- Thomas Henry Huxley (1825–1895), English zoologist and advocate of evolution, agnosticism and scientific education
- Alpheus Hyatt (1838–1902), American neo-Lamarckian
- Libbie Hyman (1888–1969), invertebrate zoologist
- Josef Hyrtl (1810–1894), Austrian anatomist
Read more about this topic: List Of Biologists