Lionel Jack Dumbleton (1905 – 25 September 1976) was a New Zealand entomologist. He was born in Hampden, New Zealand and was a founding member of the Entomological Society of New Zealand.^{[citation needed]}

One of his most remarkable biological discoveries was a new genus of caddis-fly-like primitive moths that he described as Agathiphaga (Dumbleton, 1952) and which has been subsequently raised to superfamily level as the second most primitive known living lineage of moths, Agathiphagoidea.^{[citation needed]}

In 1998 a new genus of hepialid moths was named Dumbletonius in his honour, and Hort Research has a building in Auckland named after him.^{[citation needed]}