Along with Tanaka, Yamada (山田) is also often used as a placeholder surname. It’s a comparably common name that’s also simple to read and write.

As for female placeholder given names, IMO the closest equivalent to Taro would probably be Hanako (花子). I’ve seen adverts that show sample credit cards or forms bearing these names.

For example, an ad for a Toyota financing promotion might feature the name Toyota Taro on the sample application form. Or in a Mitsubishi UFJ credit card ad, the happy-looking lady in the ad will be using a credit card that bears the name Mitsubishi Hanako.

It’s home to a very strange community unaware that their “platform” was just an image host for users of an actual social media platform. Well, at least it was before imgur recently started adding social media features and purged nsfw content.

Popular image posts from reddit would routinely get boosted (sans context) to the top of imgur’s homepage, which would attract confused, angry, and often unintentionally hilarious comments from imgur users. Iirc there was a subreddit dedicated to this phenomenon.

Edit: sp