Victor Barrio, 29, became the first matador in Spain to be killed in the ring for more than 30 years when the bull, called Lorenzo, speared him through the chest, puncturing his lung and severing his aorta.
As per tradition, the mother of the bull that kills a matador is destined to be destroyed to “kill off the bloodline”.
But thousands of furious animal rights campaigners say the bull should not be made to pay the price for the matador’s death.
Animal rights political party, PACMA, posted on Facebook: ” No rite, tradition or custom based on a succession of deaths, fed by the blood and hatred, can be good for any society.
“We only know one ethical end to end all this: the total abolition of bullfighting festivities.”
Thousands retweeted #SalvemosLorenza on Twitter, which is now trending in Spain.
One angry user said: “It’s deplorable. Human wins = hero, innocent bull wins = murderer & mother is slaughtered.”
While another said: “They are always bragging about the bravery of matadors yet when one dies, they kill the mother.”
The bull that killed Mr Barrio is understood to have already been slaughtered, while the fate of the mother remains unknown.
However local reports suggest the mother is already dead, having died of old age just a few days ago.
Award-winning matador Mr Barrio died in hospital after the 87-stone bull gored him. He is the first recorded matador death since 1985.
Bullfighting is a popular but controversial tradition in Spain, with around 2,000 fights held every year, but is falling each year.
In 2010, Catalonia became the second Spanish region to ban bull-fighting after the Canary Islands.