| "Donnie Fatso" | |
|---|---|
| The Simpsons episode | |
 Promotional image for the episode | |
| Episode no. | Season 22 Episode 9 |
| Directed by | Ralph Sosa |
| Written by | Chris Cluess |
| Production code | MABF19 |
| Original air date | December 12, 2010 |
| Guest appearances | |
| Jon Hamm as the FBI Agent Joe Mantegna as Fat Tony and Fit Tony | |
| Episode features | |
| Chalkboard gag | "Candy canes are not elf bones" |
| Couch gag | The Simpsons on the couch is depicted as an Advent Calendar. |
"Donnie Fatso" is the ninth episode in the twenty-second season of the American animated television series The Simpsons. It first aired on the Fox network in the United States on December 12, 2010. The plot revolves around an FBI agent, who helps Homer go undercover to infiltrate Fat Tony's mob. Homer agrees to help the FBI in order to reduce his prison sentence on a bribery conviction. This episode is a reference to Goodfellas as well as real-life FBI agent Donnie Brasco.
"Donnie Fatso" was written by Chris Cluess and directed by Ralph Sosa. Critics were polarized with the episode, with criticism stemming from its main plot and cultural references.
Upon its initial airing, the episode received 7.32 million viewers and attained a 3.2/8 rating in the 18-49 demographic, according to Nielsen ratings. "Donnie Fatso" featured guest appearances from Jon Hamm and Joe Mantegna.