An Aggedor was befriended by the Third Doctor, whom he met on two occasions.
Although the species was thought to be extinct, there were some Aggedor living in the deep mountains on Peladon. High Priest Hepesh found one and trained it to scare away the ambassadors of the Galactic Federation to prevent Peladon from joining. The Doctor was able to hypnotise Aggedor into overcoming his conditioning and when Hepesh attempted to command him, Aggedor killed him. Without the influence of Hepesh, Aggedor was a very loving creature, who took a great liking to the Doctor. (TV: The Curse of Peladon)
Fifty years later Aggedor was still alive. When the Doctor and Sarah Jane Smith were thrown into the temple pit the Doctor calmed Aggedor with a venusian lullaby, as he had done before. Later, he proved useful in tracking down by scent Queen Thalira who had been abducted by Eckersley and a rogue group of Ice Warriors. Once Thalira had been found, Aggedor attacked and killed Eckersley but not before being fatally wounded himself. (TV: The Monster of Peladon)
The Tenth Doctor later reminisced about hypnotising an Aggedor. (PROSE: Sick Building) Whilst being affected by the memory weave, Jo Grant and Sarah Jane Smith both remembered their encounters with Aggedor. (TV: Death of the Doctor)