The New Yorker debuted on February 21, 1925 — and its cover was graced with the first of many appearances by the magazine’s mascot Eustace Tilley. The illustration was by Rea Irvin (1881-1972), the man responsible for the eternal look of The New Yorker right down to designing the logo typeface, named “Irvin” for its creator.

In 1924, Irvin joined an advisory board to help launch The New Yorker. For the cover of the magazine’s debut issue the next year, Irvin created Eustace Tilley, a smartly attired dandy with a monocle and top hat. This amusing and worldly, yet somewhat detached, character embodied the spirit of the new publication. Tilley quickly became Irvin’s signature piece and has reappeared on the magazine’s cover every year since, with one exception–1994.

Between 1925 and 1958, Irvin’s work appeared on 169 covers of The New Yorker. Hundreds of other illustrations by Irvin were also published inside the magazine. http://www.tfaoi.com/aa/1aa/1aa398.htm (dead link)

https://en.wikipedia.org/wiki/Rea_Irvin
https://www.newyorker.com/magazine/1996/01/22/rea-irvin

Irvin had been art editor at Life, and Ross trusted
his taste, which—as others have noted—in turn shaped his
own. Ross biographer Dale Kramer describes his influence: “[Irvin]
had a quick, accurate eye for good craftsmanship. More important, he
knew what changes were necessary to make mediocre work passable and
passable work better.” Born in San Francisco, Irvin had worked as
a newspaper illustrator, stage and screen actor, comic strip artist, and
piano player before arriving at Life. Irvin’s diversity of
aesthetic experience was as essential to his invention of The New
Yorker’s visual style as Ross’s vagabond generalism was
to his conception of the subject matter. http://www.printmag.com/article/everybody_loves_rea_irvin/