Pierrot Co., Ltd., known as Studio Pierrot from 1979 to 2002, is a Japanese anime production studio mainly known for shonen manga adaptations. They currently create the famous shonen anime Naruto, and its spin-off. They also produced the Bleach anime in both of its phases, from 2009 to 2021 and then from 2022 onwards. Before the 2000s, they were best known for their Magical Girl series, such as Magical Angel Creamy Mami, Persia the Magic Fairy, Magical Star Magical Emi, Magical Idol Pastel Yumi, and Magical Stage Fancy Lala. They're also known for -among others- Dallos, the first OVA; animating the first half and first two movies of the '80s Urusei Yatsura; Kimagure Orange Road; Saber Rider and the Star Sheriffs; Yu Yu Hakusho; the Sonic The Hedgehog OVA; Fushigi Yuugi, and the DiC co-produced series The Mysterious Cities of Gold.
One of the many studios to begin as an offshoot of Tatsunoko Production, founded by former Tatsunoko staffers in May of 1979. Their first production, Nils no Fushigi na Tabi (an adaptation of The Wonderful Adventures of Nils by Swedish author Selma Lagerlof), debuted the following year. For more info, check out their ANN entry.
Known for launching the career of Mamoru Oshii. They also have a bit of a Never Live It Down streak regarding their handling of their shonen series' relationships, particularly in regards to shipping.
"Pierrot" is the French word for "clown," hence the use of a clown face as the studio's logo.