The Brothers Hop Pyleen were two wealthy brothers who attended the destruction of Earth in the year 5,000,000,000 on Platform One.
The Brothers Hop Pyleen were two reptilian humanoids, who lived on the clifftops of Rex Vox Jax in their childhood. The pair became famous and rich from inventing the Hyposlip Travel Systems. They preferred to wear fur clothes to keep their cold-blooded bodies warm. They both survived Cassandra's attack on Platform One, and left afterwards. (TV: The End of the World)
The brothers, along with the other survivors of Platform One, were later kidnapped by the Elth of Balhoon, who believed that they hadn't tried to help his brother, the Moxx of Balhoon and had abandoned him to die. They were rescued by the Tenth Doctor, and not only forgave the Elth for kidnapping them, they offered to help him. (COMIC: Reunion of Fear)