Lankascincus deignani, commonly known as Deignan's tree skink and the Deignan tree skink, is a species of lizard in the family Scincidae.

[1][2] L. deignani is named after American ornithologist Herbert Girton Deignan,[3] being originally named Sphenomorphus deignani by Kansas University's Edward H. Taylor, based on a specimen collected by Deignan from Gannoruwa Mountain on November 12, 1944.

[4] The synonym, L. greeri, was named in honour of Australian herpetologist Allen Eddy Greer.

Deignan's Lanka skink is confined to the midhills, submontane and montane forests, at 600 to 1,700 m (2,000 to 5,600 ft) of elevation.

L. deignani is found in moist leaf litter, under stones and logs in forests.