Stephen King is widely considered one of the best-selling authors of all time, with estimated sales of over 350 million copies worldwide.
R.L. Stine is also a highly successful author, particularly in the children's and young adult genres. His estimated sales are around 400 million copies, but it's important to note that this includes his Goosebumps and Fear Street series, which are aimed at younger readers.
While R.L. Stine has sold more books in total, Stephen King's sales are more significant when considering his broad appeal across different age groups and genres. He has written numerous critically acclaimed novels and has a dedicated following among both casual readers and literary enthusiasts.