Chuck is the third studio album by Canadian rock band Sum 41. The album was released on October 12, 2004. It was the last album to feature guitarist Dave Baksh before his departure from Sum 41 on May 11, 2006. Baksh later rejoined the band in 2015. Chuck peaked at No. 2 on the Canadian Albums Chart and No. 10 on the US Billboard 200, making it the band's highest-charting album until it would be surpassed by Underclass Hero in 2007.

The album's title is named after a volunteer UN peacekeeper named Chuck Pelletier who was in the Democratic Republic of the Congo where Sum 41 was filming a documentary for War Child Canada. Fighting broke out during production, and Pelletier helped the band evacuate their hotel during the fighting, as he was staying at the same hotel.

The album's lyrical content has been described as darker and more mature than the band's previous work. It also had a different sound, mixing punk rock and melodic hardcore with heavy metal. The album proved to be a success, receiving acclaim from both critics and fans, as well as selling over five million copies. Singles such as "We're All to Blame" and "Pieces" gained success on the Canadian and American charts, and the album won a Juno Award for "Rock Album of the Year" in 2005.

The band's previous album Does This Look Infected? (2002) became a commercial and critical success, and the band went on a tour in the album's support. In mid-2004, the band took a break from touring and filmed a documentary for War Child Canada in the Democratic Republic of the Congo. The film was called Rocked: Sum 41 in Congo and was released in 2005 by MTV. However, fighting broke out during the filming while the band was staying in a hotel.

"The shooting was all around us, and all these people were waiting, probably to die," said drummer Steve Jocz, reflecting on the experience. "Two UN people arrived at the scene and gave a speech about how everything would be fine," bassist Jason "Cone" McCaslin mentioned. "And then after they left, things just went crazy."

Vocalist/rhythm guitarist Deryck Whibley mentioned that he thought that a day after the UN gave an update about safety, he was expecting they would be able to evacuate. The next day, the band members woke up at 5:00 in the morning when two gunshots were fired. "We went to the hotel's restaurant to get some breakfast, when the gunfire just got closer to us," said lead guitarist Dave "Brownsound" Baksh. A U.N. peacekeeper named Charles "Chuck" Pelletier instructed the residents of the hotel to leave the restaurant. Whibley recalled, "We all just went into Cone's room, where there was around 43 other people there. We were all hiding in the bathroom and hiding on the floor." Baksh added, "Our U.N. peacekeeper was armed with a club, a new club because the price tag was still on it, but they were armed with guns".

Pelletier continued to reassure the band and others at the hotel that everything would be okay. After the crowd was in hiding, Pelletier left to get help. The U.N. continued trying to find out as much information on the gunfire as possible, but updates were few. "After a while, the gunfire seemed to start dying down, and then people started to go outside and they started talking. We seemed to be feeling pretty good, but then out of nowhere, the huge gunfire just went off," stated Whibley. "This war was so unpredictable. At one point, it sounded like it was far away, and at another point, it sounded like it was right outside the door. Then Chuck came in and told everyone to wait for the APC's to arrive. That was probably the scariest part, when we were waiting to get into the APC's." Baksh recalled, "I remember just waiting there and just wondering what the fuck was gonna happen."

Pelletier called for armored carriers to take the hotel's occupants out of the hot zone. "By then, I just kept thinking about everything we did as a band and everything I've done as a person, and I thought, 'This is it. This is how we're gonna die,'" Whibley said. After nearly six hours, the carriers arrived, and the band and the forty other civilians were taken to safety. In honor of Pelletier, the band decided to name their next album after him. Pelletier was awarded the Medal of Bravery by the Governor General of Canada for his actions.