Yamagami Lucy
Yamagami's given name is absurdly long—so long that everyone just calls her Lucy. The story goes that her parents couldn't decide on a name, so they literally listed every idea they'd come up with on the registration form. The bureaucrat who processed it apparently approved the whole thing without question, which became a running source of shame for her. She's so bitter about it that she half-jokes she became a civil servant specifically to get revenge on whoever let that slip through. Don't call her by her first name or any abbreviation if you want to stay on her good side—she genuinely hates it.
Her official name includes at least thirteen parts: Lucy Kimiko Akie Airi Shiori Rinne Yoshiho Ayano Tomika Chitose Sanae Mikiko Ichika. Though honestly, even that's just what she bothered writing down. In a crossover Drama CD with Working!!, Hiroomi Souma rattled off an even longer version that kept going and going—apparently it's become something of a running gag among other characters to see just how many names she actually has.
Content compiled by AnimeList.moe from publicly available sources.