Popular fan-nicknames for Yukari include "Sukima" ("gap"), "Yukarin" (a contraction of "Yukari-chan"), and "Babaa" (roughly, "old hag"). This latter is because she is known as one of the oldest youkai in Gensokyo.
Yukari is also often depicted with Kanako Yasaka and Eirin Yagokoro. Aside from their mature looks in fan works, this is due to their family names containing the character 八 (pronounced "Ya") which, when misread, can mean old hag. Whereas fans often refer to Cirno, Rumia, Mystia, and Wriggle as the "Bakartet," Yukari, Eirin, Kanako, and Yuyuko (or sometimes Byakuren) form the "Babartet."
In some fanworks, Yukari insists on being 17 years old. Usage in fanworks is possibly a parody of Kikuko Inoue, who claims that she is 17 years old despite being way over that age. Musou Kakyou: A Summer Day's Dream casts Kikuko Inoue as the narrator (probably Yukari), in a nod to this in-joke. Another possible reference is Yukari Tamura, who also claims that she is 17 and one of whose nicknames is "Yukarin".
Although not expressly stated, Yukari is commonly considered one of the most powerful—if not the most powerful—youkai in Gensokyo, although a few other youkai like Yuuka Kazami and Suika Ibuki have been considered to be around her level. However, she might still lose spellcard battles to humans or youkai.
Yukari is sometimes seen riding on top of a train in fan-made videos, likely due to her most powerful spellcard in SWR and Touhou Hisoutensoku, in which she summons a train to run over her opponent.
Yukari is associated with Maribel (see Maribel's page for details), although their exact relationship, if any, is unknown. Some fanworks even depict both of them as the same person.
Due to the fact she sleeps all day, many fans portray her as lazy.
Other fan works depict her as someone who is nocturnal (see below, right)
In many fanworks, Yukari constantly harassing or pranking Reimu, from wicked affection. Sometimes, it becomes a Yuri relationship. In this case, Yukari is depicted as obsessive character, stalking Reimu using the "gap" all day.
She has been known to gap random fictional characters into Gensokyo in fan works.