Taiyang Xiao Long, also known as Tai, is the father of Yang Xiao Long and Ruby Rose. He is mentioned to be a teacher at Signal Academy on the island of Patch where the girls grew up.

He was part of Team STRQ alongside Summer Rose, Raven Branwen and Qrow Branwen. He also had a relationship with Raven, resulting in Yang's birth. After her disappearance, he started a relationship with Summer that resulted in the birth of his second child, Ruby.

(Source: RWBY Wiki)