From mangas of any kind?
Naoki Urasawa, Clamp, Kaori Yuki, Hiromu Arakawa, Takehiko Inoue, Miyamoto Kano, Yoneda Kou, Sadehiro Mika and Mentaiko.
That's sum it all!
Yaoi/shounen ai: Yoneda Kou, Kyuugou, Natsume Isaku, Ogawa Chise, Kakine, Naono Bohra, Suzuki Tsuta, Yamamoto Kotetsuko, Ogura Muku, and many more.
Shoujo: Tsubaki Izumi, Matsuzuki Kou, Motomi Kyousuke, Komura Ayumi, and others i can't remember.
Nekota Yonezou, Ayano Yamane, Hinako Takanaga, Moegi Yuu
Junko
Natsume Isaku
Suzuki Tsuta
Kyuugou
Yukimura
Yoneda Kou
Ichikawa Kei
Kakine
Bubun Hanten
Tenzen Mamoko, Aoi Aki, Asou Kai, Machiya Hatoko, Kawai Touko, Susuki Tsuta, Ogura Muku, Yoneda Kou, Miyamoto Kano
Kazuya Minekura, Niagawa Yaeko ... many others, but I can't remember their names off the top of my head.
I have a few favorites but the moment I read this question Yoneda Kou shined brightly in my mind.
what are your favorites authors?