Curious George
Yet another series featuring a yellow hat, the man in the yellow hat (actually, yellow everything!) is the caretaker for George. George, originally called "Zozo," only starred in seven books by the original creators. Those 7 books though, were classics that led to numerous versions that attempted to keep the theme of the earlier works going. While George is fondly remembered, the books have the odd distinction of being based around George being disobedient, making catastrophic mistakes, and usually both! He always learns something, but honestly the fondly remembered George isn't always the best example for children.