MEIKO (メイコ) is a Japanese VOCALOID originally developed by Yamaha Corporation and distributed by Crypton Future Media, Inc.. She was one of the 4 known "Project Daisy" vocals. Her VOCALOID3 update was developed and distributed by Crypton Future Media. She was initially released in November 2004 for the first VOCALOID engine. There has since been a second installment developed for the VOCALOID3 engine, dubbed MEIKO V3. Her voice is provided by the Japanese female singer-songwriter, Meiko Haigō (拝郷 メイコ Haigō Meiko).

As of August 31, 2019, it was announced that there would be no further installments with the VOCALOID program. Instead Crypton is focusing on their own program, Piapro Studio. As of August 2024, however, a refined and retuned edition of MEIKO's original VOCALOID3 voicebank, titled MEIKO SP, was released for the PIAPRO CHARACTERS SUPER PACK; a set of Japanese voicebanks developed for the Piapro Studio for V4X and VOCALOID4 engines.

This release was noted to improve MEIKO's overall balance of tone and pronunciation.

"MEIKO" comes directly from her voice provider's name, "Meiko Haigō" .

MEIKO's codename was "HANAKO"; it likely came from "Hanako Yamada (山田花子)", a placeholder name for female characters, and the Japanese equivalent to "Jane Doe". "Megumi" was also a name considered during her development.

She is often misnamed Sakine Meiko by fans. The name originates from the eponymous derivative character, depicted as herself in her younger days.

MEIKO is very outgoing and happy. She acts like a good mother to the Vocaloids. She is often described as party mom and cool mom to the Vocaloids. She loves to have a party dance with her friends.