Theophylact Botaneiates is only mentioned in the history of John Skylitzes for the year 1014, during Emperor Basil II's wars against Bulgaria.
[1] In that year, Emperor Basil II was assaulting the Bulgarian positions in the pass of Klyuch (Kleidion in Greek).
Botaneiates and his son Michael met the Bulgarians and defeated them in the vicinity of the city, after which he joined the main imperial army.
He carried out his mission with success, but on his way back to the Emperor's camp his army was ambushed by the Bulgarians and Botaneiates himself was killed, either by arrows and stones, according to Skylitzes' account, or run through by the spear of Samuel's son Gavril Radomir, as reported in a side note to the original manuscript of Skylitzes.
[4] According to Skylitzes, the death of Botaneiates alongside most of his men greatly disheartened Basil, so that the emperor, despite his victory at Kleidion, halted his campaign and turned back to his base, Mosynopolis.