Sir John Tenniel (; 28 February 1820 – 25 February 1914) was an English illustrator, graphic humourist and political cartoonist prominent in the second half of the 19th century. An alumnus of the Royal Academy of Arts in London, he was knighted for artistic achievements in 1893, the first such honour ever bestowed on an illustrator or cartoonist.

Tenniel is remembered mainly as the principal political cartoonist for Punch magazine for over 50 years and for his illustrations to Lewis Carroll's Alice's Adventures in Wonderland (1865) and Through the Looking-Glass, and What Alice Found There (1871). Tenniel's detailed black-and-white drawings remain the definitive depiction of the Alice characters, with comic book illustrator and writer Bryan Talbot stating, "Carroll never describes the Mad Hatter: our image of him is pure Tenniel."