Mark Forsyth (born 2 April 1977) is a British writer of non-fiction who came to prominence with a series of books concerning the meaning and etymology of English words.

He is the author of best-selling books The Etymologicon, The Horologicon, and The Elements of Eloquence, as well as being known for his blog The Inky Fool. Forsyth's earlier work was based around the meaning of words and more specifically, obscure and out-of-use words. His first two books were featured on BBC Radio 4's series Book of the Week.

In June 2012, Forsyth gave a TEDx talk entitled "What’s a snollygoster? A short lesson in political speak".

Forsyth attended Winchester College in Winchester, Hampshire, England from 1990 to 1995. He also studied English Language & Literature at Lincoln College, Oxford University, from 1996 to 1999.

As a self-described journalist, proofreader, ghostwriter and pedant, Forsyth started a blog called Inky Fool in 2009 as a forum to share his love of words. His posts often involve an exploration of words; where they come from and how they relate to each other. "Etymology is fun," Forsyth said in a Skepticality interview. "Some people talk about the true meaning. I just find it interesting and delightful and often just very, very funny. That's the main thing I love about etymology."

The popularity of Inky Fool led to Forsyth's first book publishing deal in 2011 with Icon Books. In The Etymologicon: A Circular Stroll Through the Hidden Connection of The English Language, Forsyth explains the meanings and derivations of well-known words and phrases, and explores the strange connections between words in a stream-of-consciousness fashion. The book's title, originally called Point Blank Check Mate: The Inky Fool's Book of Word Association, references the poet John Milton who purportedly invented the word "etymologicon" to describe a book containing etymologies. The book's structure leads the reader to "unexpected coinages and devious linkages, sexy, learned and satisfyingly obscure." It is, according to reviewer Karin Schimke, "a cursory run through history presented with a wry eye and a peculiar sense of humor." Reviewer Robert McCrum wrote: "Not since Eats, Shoots & Leaves has a book about language...attracted so much attention in bookshops, running through successive reprints." The Etymologicon was a Sunday Times No. 1 Bestseller in January 2012.

While The Etymologicon falls into the category of edutainment, the examples Forsyth includes in the book are well researched and supported by evidence. His goal was to include as much scholarly information as "lightly" as possible. Forsyth researches words and phrases as far back to their original sources as he can find. "Often, the joy of the research," he said in a Chicago Tribune interview, "is finding examples of the original usages that have been lost for centuries. For example, humble pie used to be umble pie because the umbles were the innards of a deer (so it was the poor man's equivalent of venison pie). I actually found a recipe book from 1727 deep in the bowels of the British Library that gave instructions on how to make it. So I did. And it was delicious."

In The Etymologicon, Forsyth cautions against what he calls "the danger of inductive reasoning" when determining the commonality among diverse languages. Some patterns in language, he asserts, are mere coincidence and linguists meticulously document specific examples of word and sound changes to determine whether or not disparate languages are, indeed, connected.