I have deleted these examples because they don't fit the trope. Phillip Ontakos is just a pun ("fill up on tacos"). The other three reference the trope's name (Sue Donym), not the trope itself. For the trope itself, we need someone like Susan Realname, who pretends to be Sue... Donym.

Advertising

• In one Taco Bell commercial, a man named Phillip Ontakos is working at cubicle 399. It was advertising their $3.99 Taco special.

Other

• One of the people who routinely set the New Scientist's weekly puzzles is called, apparently for real, "Sue Denham".
• Similarly, 1970s & 80s SF author P.S. Nim.
• TV Tropes has a troper named Suedenim.