The killing of Zimbabwe's beloved Cecil the lion by an American dentist has sparked outrage worldwide.

The 13-year old was shot wounded with a bow and arrow, tracked for 40 hours, and eventually shot dead outside park territory.

Last night US Talk show host Jimmy Kimmel host took a few minutes of his opening monologue to talk about the tragedy.

Deriding Walter Palmer, the Minnesota dentist who paid $50,000 to illegally kill Cecil, he wonders what motivated the act:

"Is it that difficult for you to get an erection that you have to kill things that are stronger you?"

he goes on to suggest he may be the most hated man in America after Bill Cosby.

Kimmel says it is important that something good come out of the story, and with a faltering voice implores his viewers to donate to Wildlife Conservation Research Unit at Oxford University, who monitor lions in the park.

Donations can be made at wildcru.org.