Hankins, 34, was put to death by lethal injection Tuesday night at a Texas prison in Huntsville. He was sentenced to death in 2002 for killing two of his wife's children in 2001.
Amnesty International said in a statement that Hankins was the 16th person to be executed in Texas this year, out of a national total of 30.
The organization, which opposes the use of the death penalty and has urged Perry to work to end its use in Texas, also noted it was the 1,166th execution to be carried out in the United States since judicial killing resumed there in 1977, with Texas accounting for 439 of them. Ohio executed Daniel Wilson Wednesday, bringing the national total to 1167.