Vriha T'Rehu was a villainous Romulan introduced in the Star Trek novel The Romulan Way.
Born after the exile fleet from Vulcan arrived in the Romulan system and settled the twin worlds of Romulus and Remus, she was the northern continent's Grand Councillor after the death of her father. Welcoming scientists who specialized in fertility and cloning to her country, she was able to raise a large army in a short amount of time and then set about conquering smaller territories. She was able to eventually to force the ruling council to accept her as their leader, going so far as to have the elderly leader S'task killed on the floor of the Senate he had earlier founded. Even though S'task was 248 years old at the time, his death was still seen as shocking to the populations of both Romulus and Remus.
Eventually T'Rehu took the title of Vriha, and became the Queen of both worlds. During her time as Queen she increased the quotas that the Remans were forced to mine for the Empire, informing them that they would either work or die.
T'Rehu's rule lasted 18 years. The eastern continent of ch'Havran, or Remus, began to chafe under her rule as she seriously neglected the planet, but the Remans were able to increase their population without medical aid, and fielded a large army that defeated T'Rehu in battle and killed her on the plains of Aihai on Romulus. Following her death the government was reformed to become the Romulan Star Empire.