Sacrificial lamb

In 2004, Howard Mills was considered a sacrificial lamb candidate for the U.S. Senate from New York against Chuck Schumer.

In cinema and literature, a "sacrificial lamb" is a supporting character who's murdered by a villain, which prompts the protagonist to avenge them.

The virtuous hero mourns the sacrificial lamb's death, foiling the wicked villain who celebrates their enemy's defeat.

A similar trope is the Women in Refrigerators, where the male hero's girlfriend, sister, or mother gets murdered.

In modern media, examples include Anthony Edwards' character Goose in Top Gun, as well as Phil Coulson in The Avengers.