Thymbraeüs was the twin brother of Antiphas, both children being the sons of Laocoön. They and their father were crushed to death by sea-serpents. His name may be derived from thymbra, 'savory', a fragrant but bitter-tasting herb.
One can only guess at the implied significance of this (the crushing of a young life seen as both fragrant and bitter). Thymbraeüs was also one of the by-names of Apollo, but this derives from the town of Thymbre, not from Thymbraeüs.