Veridis

 was a planet located in E-Space. For a time, Veridis was a planet where death was constantly reversed by a machine. The Fourth Doctor and Romana II sacrificed their lives to destroy the machine, leaving their companion Adric to live a long full life on Veridis.

History
After the teenager Asun fell into a river and drowned, her grandfather Tivorg became obsessed with bringing her back to life. A few days later, he took her body from its grave and began experimenting on it. After some time, he succeeded.

Tivorg became a hero on Viridis. After a Viridian died, he would use his machine to bring them back. Although they stopped dying, the Viridians continued to have children. The population of Viridis quickly grew.

A few months after the cure for death was discovered, Viridis was in chaos. The government had been overthrown by rebels and rioters had begun a siege on Tivorg's house. The Fourth Doctor, Romana II, Adric, and K9 Mark II came to Viridis and learned of its current situation. The Doctor decided to destroy the machine to bring peace to Viridis. The Doctor and Romana died doing so, leaving Adric and K9 stuck on Viridis without anyone to pilot the TARDIS.

Viridis became normal again and the TARDIS gradually dissolved into nothing. For years, Adric lived practically alone with a powerless K9. Eventually, after Tivorg's death, Adric encountered Asun at a market. They began dating and after some time married. Adric and Asun had two children: Varsh and Neegat. Adric studied and became a doctor. After their children grew up, Adric and Asun travelled the world helping people. Varsh had a son. After Asun contracted a terminal illness, she told Adric to find someone to live with after her death. Adric did just this and married Reebac.

Adric began having dreams of about destroying N-Space. Feeling that history had gone wrong, Adric constructed a time machine with crystals salvaged from the TARDIS and used it to go back in time to try to revert the Doctor and Romana's death. He recorded a message for his grandson before doing so. (AUDIO: A Full Life)