Encyclopedias, Almanacs, Transcripts, and Maps
- Heat (Stress) Index
- Heat Pumps
- Heaviside, Oliver (1850–1925)
- heavy metal
- Heavy Metals and Heavy Metal Poisoning
- Heavy Metals Precipitation
- Hedge Sparrows (Prunellidae)
- Hedgehogs
- Hegel, G. W. F.
- Heilbroner, Robert Louis (1919 – ) American Economist and Author
- Heiler, Friedrich
- Heimdallr
- Hejira
- Hekate
- Hellenistic Age
- Hellenistic Religions
- Hellespont
- Hells Canyon
- Helmholtz, Hermann Von (1821–1894)
- Hemichordata (Hemichordates)