Tyrannodoris nikolasi is a species of sea slug, a polycerid nudibranch, a marine gastropod mollusc in the family Polyceridae.

[1] Tyrannodoris nikolasi is a predominantly dark green animal with light green to yellow horizontal stripes or more continuous superficial pigment.

The gills and rhinophores are dark blue or violet.

It reaches approximately 15 mm in length.

Like other nudibranchs in the genus Tyrannodoris, it is carnivorous, feeding on other seaslugs.