Light Yagami's actions in "Death Note" have a significant impact on the themes of justice and morality in the series. His transformation from a seemingly righteous individual to a power-hungry and morally ambiguous character challenges the traditional notions of justice and morality. By taking on the role of judge, jury, and executioner with the Death Note, Light blurs the lines between right and wrong, posing thought-provoking questions about the nature of justice and the consequences of absolute power. Ultimately, Light's actions serve as a cautionary tale about the dangers of unchecked power and the complexities of morality.