Cecil, who reigned over Hwange Nati

Cecil, who reigned over Hwange National Park, was mourned by animal activists and celebrities in the days after the news broke.

Late night host Jimmy Kimmel was one of Palmer's most vocal critics.

On his show Tuesday night, Kimmel blasted Palmer for killing the lion and urged viewers to donate to the wildlife organization that was tracking Cecil.

By Thursday, Oxford's Wildlife Conservation Research Unit had received more than $150,000 in donations from 2,600 donors, The Wrap reported.

"Jimmy Kimmel implored his millions of listeners in the U.S.A. to make donations to support our work on lions, and conservation more widely," WILDCRU director David McDonald in a statement. "We are so grateful for this and for the up-welling of support for our work worldwide.