Martin Gardner (21 October 1914 - 22 May 2010) was an American mathematics and science writer. He specialized in "recreational mathematics", and for many years wrote the column Mathematical Games in Scientific American magazine. He also studied magic, pseudoscience, literature, philosophy, and religion. Gardner was also a prolific author, and wrote numerous books across many subjects (The Annotated Alice, a critical edition of Alice's Adventures in Wonderland being one of the most famous). On the subject of calculus, Gardner revised Silvanus Thompson's Calculus Made Easy, a book that approaches calculus as something that is actually quite easy to understand - if it's not over-mystified by those who would teach it.
Gardner wrote a great deal on the paranormal and was a harsh critic of the Human Potential Movement. He was also a longtime, prominent opponent of Israeli magician/"psychic" Uri Geller. He also wrote a skeptical study of the Urantia Book: Urantia, The Great Cult Mystery.
 Religious beliefs
Gardner was unusual among prominent skeptics for being a theist (though not a Christian). It's believed that Gardner coined the term "fideist" - meaning someone who chooses to believe in a god or gods because it is comforting, and not because there is evidence, as laid out in his essay Why I Am Not An Atheist.
 Fads and Fallacies in the Name of Science
Gardner's book Fads and Fallacies in the Name of Science, (originally published in 1952, later updated and republished in its current form in 1957), is regarded as a seminal work of the skeptical movement. It describes a number of the popular forms of woo that were current in the day, including: the works of Wilhelm Reich and L. Ron Hubbard, American racism before the civil rights movement, and Christian fundamentalism, which he addressed well before its heyday in American politics several decades later.
The book may appear dated, given that it was written in the 1950s, but it describes the origins of much modern-day woo, and a reader may come away feeling that gullibility and hucksterism are universal constants, and that the snake oil peddlers of the 1950s are little different to those of modern times. The woo merchants of old spread their strange ideas via self-published books and pamphlets, while the modern crank opts instead for garish websites and payment via credit card or PayPal. Plus, it can be very entertaining to read about hollow Earth theories and the rather strange ideas of Madame Blavatsky and Charles Fort.
 On Gardner's death at age 95 after a life well lived
“”Death is probably starting to regret challenging Martin Gardner to a game of his choice.