Honorary Membership was limited to 10 from 1890-1900, and to 15 from 1901 onwards. Corresponding Membership was a lesser class of Honoris causa membership in the early years. A few honorary members, such as Barnard, were first made corresponding members for a short time before being recommissioned as honorary members.
| Nation(s) | Start | End | |
|---|---|---|---|
| Hubble, Dr. Edwin Powell | USA | 1951 | 1953 |
| Holden, Dr. Edward S. | USA | 1891 | 1914 |
| Hogg, Dr. Helen S. | Canada | 1987 | 1993 |
| Hirayama, Prof. Kiyotsugu | Japan | 1907 | 1943 |
| Hertzsprung, Prof. Ejnar | Denmark | 1946 | 1967 |
| Henry, M. Paul | France | 1894 | 1905 |
| Hawking, Dr. Stephen W. | England | 1985 | 2018 |
| Harrison, Mr. Henry | USA | 1913 | 1929 |
| Hale, Dr. George Ellery | USA | 1900 | 1938 |
| Greenwood, Cpt. W. Nelson | United Kingdom | 1898 | 1906 |