Goniobranchus lekker is a species of colourful sea slug, a dorid nudibranch, a marine gastropod mollusc in the family Chromodorididae.

[2][3] This species occurs in Natal, South Africa, Madagascar, Réunion and the Seychelles.

[4] Goniobranchus lekker has a complex colour pattern consisting of a translucent white mantle which at the edge grades into opaque white, then light purple with elongated dark purple spots and finally an orange margin.

The middle of the back has raised white tubercles which are somewhat clustered into groups.

[5] There are a number of species with similar colour patterns.