Harbert

Ser Harbert is the former castellan of Storm’s End, already old in 278 AL. He is the great-uncle of Robert, Stannis and Renly Baratheon. His family name is not stated so it is not clear if Ser Harbert is a Baratheon himself.

Since Cortnay Penrose was castellan when Renly was made Master of Laws, it is clear that Harbert was dead before Renly achieved manhood.