Things to Consider:
1) Does it have multi-media presence – print, TV, radio, film, digital and internet?
2) Is it known and popular within the last 50 years and most likely to endure in the next 50 years?
3) Did it spawn games, toys and other merchandise i.e.T-shirt, mug, bedsheet, poster et al?
4) Is its origin constantly rebooted, revised or retold? Its toys upgraded and re-released?
If YES to all 4 questions, then, it must really be ubiquitous.
Ubiquitous: Present everywhere
Fictional: invented;literary book characters excluded UNLESS it appeared in a Comic Book or in an Animated Film
Characters for Children: Self-explanatory otherwise ask your doctor or mother or kids around.
Please add other characters as you deem fit. I started off the list with 30 just to get things going. The list is nowhere definitive, riddled as it is by my personal biases and/or limited knowledge.
Acknowledgment: All Images Were Sourced from the Internet. Thanks.