Scott McCloud is a cartoonist and he has written non-fiction books about comics and has given a TED talk on the subject.
His personal circumstances (his work as a cartoonist) means that his non-fiction work on comic theory is given more weight.
However, the influence of McCloud’s work as a cartoonist on how serious his non-fiction writing is taken could be a problem. Just because someone is an artist in a particular field does not necessarily mean that their theories should have more influence. McCloud’s background as a cartoonist could mean he is too close to the subject of comics to theorize objectively. His ideas could have more influence regardless of the strength of his arguments and evidence.