Ramalina sanctae-helenae is a species of saxicolous (rock-dwelling), fruticose lichen in the family Ramalinaceae.

It was formally described as a new species in 2008 by Dutch lichenologist André Aptroot.

The type specimen was collected by the author on the north slope of Prosperous Bay Plain at an elevation of 280 m (920 ft); there, it was found growing on basalt.

The fruticose thallus of the lichen, initially shrubby, becomes pendant with age, reaching lengths of up to 40 cm (15.7 in), although typically it is smaller, up to about 7 cm (2.8 in).

According to the author, the presence of various chemical strains of the lichen suggest that it is undergoing speciation.