The Mud Boy (Spanish: El niño de barro) is a 2007 Spanish-Argentine thriller drama film directed by Jorge Algora [es] which stars Maribel Verdú, Daniel Freire, Chete Lera, and Juan Ciancio.

Set in 1912 Buenos Aires against the backdrop of the story of the Petiso Orejudo serial killer, the plot tracks 10-year-old boy Mateo, haunted by nightmares, and the main suspect behind a trail of brutal killings in the city.

[7] Juan Pablo Cinelli of Página/12 assessed that Algora is right to opt for fiction rather than documentary accuracy.

[8] Jonathan Holland of Variety considered that "the excesses of the story are reined in by intelligent treatment, with thoughtful perfs, fine period atmospherics and a well-achieved sense of dread making up for occasionally clunky direction and loose scripting".

[9] Parana Sendrós of Ámbito Financiero deemed the film to be worth your time, considering that the balance is positive "due to the way [the film] is made, the intelligence with which it tells the story, and the light it sheds on the always current issue of the treatment of children".