There are many famous Johnsons, but two immediately come to mind:
* Samuel Johnson: This is the most likely answer. He was a prominent English writer and critic in the 18th century. He is most famous for his work on The Rambler, The Idler, and The Dictionary of the English Language. He did not write for The Spectator, although this periodical was highly influential and popular during his lifetime.
* Lyndon B. Johnson: This is the 36th president of the United States. He did not write for any periodicals in the traditional sense.
Therefore, the answer to your question likely depends on which Johnson you are referring to. However, if you meant Samuel Johnson, it is likely that he did not write for The Spectator.