Sirak

Sirak was a student at the sith academy on korriban during the new sith wars. When Darth Bane rashly challenged sirak in an attempt to prove himself Sirak deafeted him nearly killing him, after this defeat bane sought secret trainig from both Githany and Kaslim he then challenged Sirak again and this time was to much for him Bane however did not kill him

Scources
Darth Bane: path of destruction