Here’s an ad from March 11, 1945 with an assortment of Walter Lantz characters from cartoons and comic books.
Eight Ball and Oswald were no longer part of Lantz’s theatrical world, while Miranda Panda wouldn’t appear on screen for a few years. Milo first appeared in “Crow Crazy” in 1945.
Unfortunately, the artist isn’t identified. You can click on the picture to make it bigger.