Jean Baseilhac known as Brother Côme (or Cosme) (born 1703 in Pouyastruc, Tarbes - died in 1781) was a French surgeon and lithotomist.

In 1767, through her solicitations from the Comptroller General Bertin, Jean Baseilhac, convinced of the usefulness of the courses she gave, obtained a patent for the famous midwife Angélique du Coudray.

Jean Baseilhac is the inventor, among other instruments, of the lithotome, the operation of which limited the drawbacks and dangers of previous methods - in particular that of Jacques de Beaulieu (1651-1714).

A controversy opposed him to the famous surgeon Claude-Nicolas Le Cat about his practice of the hidden lithotome (Parallel of the lateral size with that of the hidden lithotome, published by Le Cat in 1766 in Amsterdam under the pseudonym A.-P.

[4] The figure of Brother Cosme appears several times in Diderot, notably in Jacques le fataliste where the Master attributes to him a successful size operation and in his letter to Sophie Volland du December 1, 1765.