It is a very known fact that CLAMP is a popular group of 4 females. For one thing they are most famous for their beautiful drawings, creativity, and twists in their mangas! CLAMP's works are mostly Shoujo manga (Girls' comics) but they also do Shounen manga (Boys' comics).
The Others who left:
Tamayo Akiyama: She was the leading artist in Clamp's first commercial
release 'CLUSTER'. But, throughout
the years, she became heavily influenced by Mokona Appapa's style (still is too). Because of that she left the group leaving Mokona to take over as Clamp's leading artist. Tamayo is now a solo mangaka.
Works: CLUSTER (1991-1995), DERAYD (1993) plublished by Shinkigensha, MOURYOU KIDEN (1993-1994) and CYBER PLANET 1999: HYPER RUN (1995-1997) published by Asuka Comics DX. Current work? For more info and pictures, go here: Tamayo Akiyama Temple, Anime Art's Cluster Image Gallery, Anime Art's Mouryou Kiden Image Gallery
Leeza Sei: The same same thing had happened to her also, she was the artist for 'COMEBINATION'. Leeza Sei is now writing under the name of Iba Takeo. Her style has changed dramatically.