Propaganda cartoons play a big role in war by educating service members, encouraging the purchase of war bonds, and rallying the home front. The heyday of American propaganda cartoons was easily World War II, and a motley assortment of characters have been used to win the wars.
As a note, many of the war cartoons were deliberately racist towards the people of enemy nations, so expect some offensive imagery when viewing.
1. Private Snafu and his cigar-smoking Army fairy
Snafu was a young Army private who constantly got himself into trouble by complaining, shirking duty, or avoiding medicine and immunizations. In "Three Brothers," Snafu wishes he had one his brothers' jobs, and the cigar smoking fairy shows up to show Snafu what his brothers, Pvt. Tarfu and Pvt. Fubar, are doing for the war effort. Snafu was voiced by Mel Blanc, the voice of Bugs Bunny.
2. Willie and Joe
Drawn by Army Sgt. Bill Mauldin, Willie and Joe were characters Mauldin used often to show the rigors in the field. Originally assigned to the 45th Infantry Division, Mauldin was soon assigned to the Stars and Stripes for which he drew six cartoons a week. His cartoons got him in serious trouble with Gen. George S. Patton, but the troops loved his work, especially the war weary Willie and Joe.
The Man of Steel did his part in World War II. Superman was generally depicted as a newspaperman in the States, fighting spies and saboteurs. But, he did take the fight to the enemy a few times, like in "The Eleventh Hour" when he began sabotaging Japanese industrial efforts.
4. Donald Duck and the Disney crew
Most of the Disney crew joined the war effort in different ways. Donald Duck famously took the fight to the enemy though. Oddly, the duck famous for his sailor uniform was typically depicted as being in the Army. Donald was even airborne. He makes his first jumps in "Sky Trooper" above, and eventually conducted a solo combat jump into Japan.
5. Annie Awful – The killer, sexy mosquito
Awful Annie, and mosquitoes like her, were depicted as waiting on cots for service members who neglected to hang anti-mosquito nets. The mosquitos, and the malaria they carried, were some of the deadliest killers in the war.
6. The Axis leaders
Of course, real world characters were recreated in the cartoon world, and the depictions of Axis leaders were not very flattering. In "The Ducktators," Hirohito, Mussolini, and Hitler get depicted as zealous ducks. Other Nazi leaders were ridiculed beside Hitler in "Education for Death."
7. Looney Tunes and the Gremlins
Like the Disney characters, Looney Tunes characters joined the war. In "Falling Hare," Bugs Bunny goes up against gremlins that are trying to damage Allied aviation equipment.
Popeye the sailor man joined the military in World War II. Predictably, he joined the Navy. He appeared in a lot of cartoons including "Many Tanks," and "Seeing Red, White, and Blue." In the above video, "A Jolly Good Furlough," he gets to visit his nephews and see the jobs they do in home defense.
9. Mr. Hook
Mr. Hook was part of a short-running series that began in 1943 where a vet of World War II looked back at his time in the conflict and described his exploits to his son. The dad would tell his son the importance of war bonds to America's eventual victory and then celebrate all the money they made off the bonds when they finally matured.