Wikipedia
Thumelicus (born 15 AD; died before 47 AD, probably in 30 or 31) was the only son of the Cherusci leader Arminius and his wife Thusnelda, daughter of the pro-Roman tribal leader Segestes.
In May, 15 AD, Arminius besieged Segestes at his stronghold, where Thusnelda, then pregnant, was staying. The Roman commander, Germanicus, a nephew of Emperor Tiberius, broke through the siege and took her prisoner. Thusnelda and the infant Thumelicus were presented in Rome in the Triumph Germanicus was allowed to celebrate in May 17 AD. Afterwards, the captives were spared, but were sent to exile in Ravenna, where Thumelicus probably was raised and trained as a gladiator.
Tacitus promises to recount his fate "at the proper time," i.e., when his Annals treat the year in question — but there is no further mention in the extant copy. A major gap exists for 30 and 31 AD, however, so it could be that Thumelicus was killed in the arena at the age of 15 or 16.