Monchichi is a line of Japanese stuffed toy monkeys from the Sekiguchi Corporation, and they were first released in 1974. They were licensed by Mattel in the US until 1985, and later distributed worldwide directly by Sekiguchi. Three television series were produced based on the characters.
Monchhichi was created by Yoshiharu Washino on January 25, 1974, as an improvement to the already successful "Kuta Kuta Monkey" (Exhausted monkey). Sekiguchi claims they created these characters in order to inspire respect and love in the young (Japanese) children and adults, their name is derived from the words "Mon" which translates to "Mine" in French and "Chhichi" which closely resembles the sound a child's pacifier would produce according to Japanese phonetics, also the resulting word has a similar sound to the word "Monkey" in English.
Exportation of the doll line started in 1975, towards West Germany and Austria. The following years would see the Monchichi line marketed in all of Western Europe. The original name was changed to "Chicaboo" in the United Kingdom, to "Mon Cicci" in Italy, to "Kiki" in France and to "Bølle" in Denmark. The height of the Monchichi dolls' popularity was in Germany during the 1980s, surpassing even the Japanese figure sales during this period.
The Monchichi doll line reached the North American shores in 1980. Mattel bought the license for the toy line. The American cartoon series Monchhichis was produced by Hanna-Barbera in 1983 and aired on ABC (as part of The Monchhichis/Little Rascals/Richie Rich Show) in an effort to promote the doll line. The line was dropped by Mattel due to poor sales in 1985, but was reintroduced during Monchhichi's 30 anniversary in 2004 by Sekiguchi. As of 2013, Monchhichi dolls are still available in the United States from retailers such as Target.
Source and more info: Wikipedia.
What's it worth? Take a look at this Monchhichi price guide: sold listings for a value indication.