Michael David Spivak is a mathematician specializing in differential geometry, an expositor of mathematics, and the founder of Publish-or-Perish Press.
Author of The Hitchhiker's Guide to Calculus. ISBN 09-014098-23-3
Also inventor of The Spivak pronouns, which are a proposed set of gender-neutral pronouns in English. They are used as non-sexist language by some people who dislike the more common alternatives "he/she" or singular they.
The (new) Spivak pronouns are formed from the pronoun "they" by dropping the "th".
Mickael Spivak Photography (but is this the same person?)