Jenkins, Griffith Parry (1860-1940), amateur observer, popular lecturer, one time resident in Llangefni.
Jones, John (“Y Seryddwr”, 1818-1898), amateur astronomer, originated from Dwyran.
Jones, William (1675-1749) FRS, mathematician, some work on astronavigation, originated from Llanfihangel-Tre’r-Beirdd.
Lewis, John Robert (1731-1806), also known as Sion Robert Lewis and as John Roberts, Holyhead, ran a nautical academy, published books and produced almanacs (with astrological as well as astronomical content).
Roberts, Robert (1777-1836), Holyhead, ran a nautical academy, built observatory, published books and produced almanacs (with astrological as well as astronomical content), son of John Robert Lewis.
Private observatory of Robert Roberts, Holyhead (early 19th century).
Private observatory of Rev. Maldwyn Parry, Penmon (c. 1960s).
Private observatory of Philip Curtis, Newborough, with 8-inch reflector