Editing List of biologists (section)

=== Ha ===
*[[Ernst Haeckel]] (1834–1919), German physician, zoologist,<ref>Abbreviation in zoology: Haeckel</ref> and evolutionist who argued that "ontogeny recapitulates phylogeny"
*[[Hermann August Hagen]] (1817–1893), German entomologist<ref>Abbreviation in zoology: Hagen</ref>  specialised in [[Neuroptera]] and [[Odonata]]
*[[J. B. S. Haldane]] (1892–1964), British (later Indian) biologist known for work in physiology, genetics, evolutionary biology and mathematics; co-founder of population genetics
*[[John Scott Haldane]] (1860–1936), Scottish physician and physiologist who made many important discoveries about the human body and the nature of gases 
*[[William Donald Hamilton]] (1936–2000), British evolutionary biologist who provided a rigorous genetic basis to explain altruism
*[[Philip Handler]] (1917–1981), American nutritionist and biochemist who discovered the tryptophan-nicotinic acid relationship.
*[[Sylvanus Charles Thorp Hanley]] (1819–1899), British conchologist and malacologist<ref>Abbreviation in zoology: Hanley</ref>
*[[Arthur Harden]] (1865–1940), British biochemist who studied the fermentation of sugar and fermentative enzymes
*[[Thomas Hardwicke]] (1755–1835), English soldier and naturalist who collected numerous specimens
*[[Alister Hardy|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, author of ''Fauna Americana'' and ''American Herpetology''
*[[Denham Harman]] (1916–2014), American biogerontologist, father of the free radical theory of aging
*[[Ernst Hartert]] (1859–1933), German ornithologist who studied hummingbirds
*[[Gustav Hartlaub]] (1814–1900), German physician and zoologist who studied exotic birds
*[[Hamilton Hartridge]] (1886–1976), British eye physiologist who invented the continuous-flow method for fast reactions
*[[Karl Theodor Hartweg]] (1812–1871), German botanist<ref>Abbreviation in botany: Hartw.</ref> who collected plants from the Pacific region from Ecuador to California
*[[Leland H. Hartwell]] (born 1939), American geneticist known for discoveries of proteins that control cell division
*[[William Harvey]] (1578–1657), British physician who demonstrated the circulation of blood
*[[William Henry Harvey]] (1811–1866),<ref>Abbreviation in botany: Harv.</ref> Irish botanist and phycologist who specialised in algae
*[[Hans Hass]] (1919–2013), Austrian biologist and underwater diving pioneer who studied coral reefs, stingrays and sharks
*[[Frederik Hasselquist]] (1722–1752), Swedish naturalist who collected specimens for [[Linnaeus]] in the Eastern Mediterranean
*[[Arthur Hay, 9th Marquess of Tweeddale|Arthur Hay]] (1824–1878), Scottish soldier and ornithologist who collected  birds, insects, reptiles and mammals