Yes. My son spent several months in a cancer ward. ... His best (and only, to my memory) visit from an "outsider" was an honest-to-goodness Santa Claus in the nicest Santa outfit I'd ever seen.

My son's Wish (from Make-A-Wish) was to visit Spider-man. He was very much into superheroes. Although we did get to see him on a "wish-trip" to Universal Studios, he was too small for the Spider-man 3-D ride by about four inches. We would have loved to have a hospital visit by superheroes ... but alas, I think the controlled entry nature of the cancer ward made it so many there at the hospital "just to visit" ended up in other areas.