“I have been accused of being a nasty old sexist-male-Chauvinist-pig, for the wording in D&D isn’t what it should be. There should be more emphasis on the female role, more non-gendered names, and so forth. I thought perhaps these folks were right and considered adding women in the ‘Raping and Pillaging[’] section, in the ‘Whores and Tavern Wenches’ chapter, the special magical part dealing with ‘Hags and Crones’, and thought perhaps of adding an appendix on ‘Medieval Harems, Slave Girls, and Going Viking’. Damn right I am sexist. It doesn’t matter to me if women get paid as much as men, get jobs traditionally male, and shower in the men’s locker room. They can jolly well stay away from wargaming in droves for all I care. I’ve seen many a good wargame and wargamer spoiled thanks to the fair sex. I’ll detail that if anyone wishes.”

From D&D Co-Creator Gary Gygax was Sexist. Talking About it is Key to Preserving his Legacy.

There's a rant from him somewhere about women running the hobby by... existing or something

The common example is how entire races are "evil" like goblins and orcs.

https://www.dragonsfoot.org/forums/viewtopic.php?t=11762&start=77