The Triangle of Guillain and Mollaret was described in 1931 by the French neurologists Georges Charles Guillain (1876-1961) and Pierre Mollaret (1898-1987) 1) 2) They are also known respectively for defining what is now known as Guillain-Barré syndrome and Mollaret's meningitis.

1)
Turgut AÇ, Tubbs RS, Turgut M. Georges Charles Guillain (1876-1961) and Pierre Mollaret (1898-1987) and their legacy to neuroanatomy: the forgotten triangle of Guillain-Mollaret. Childs Nerv Syst. 2021 Feb;37(2):349-350. doi: 10.1007/s00381-018-04033-8. Epub 2019 Jan 4. PMID: 30610482.
2)
Guillain G, Mollaret P. Deux cas de myoclonies synchrones et rythmées vélo-pliaryngo-oculo-diaphragmatiques. Le problème anatomique et physio-pathologique de ce syndrome. Rev Neurol (Paris). 1931;2:545–566.