As per Wikipedia, Living Dead Dolls are a line of horror dolls first produced as handmades in 1998 in the United States by Ed Long and Damien Glonek, and commercially manufactured by Mezco Toyz since 2000. Living Dead Dolls are ten inches tall, made of plastic, with fabric clothing, and come packed in coffin-shaped boxes with death certificates. Each doll has a different cause of death, which is usually described in doggerel verse on the certificate. While the dolls are occasionally inspired by real people such as Lizzie Borden, they are described explicitly as dolls, not representations of actual dead children, and are aimed at an adult audience aged upwards of 15 years.
The dolls faced backlash in Ireland and Greece - the Greek government going as far as to ban them and release a statement claiming "[the dolls are] serious threat to the smooth formation and development of the child's personality and mental health." as well as almost being banned in Singapore.
Dolls are released in series, and extremely sought after dolls are often rereleased and redesigned in Resurrection series. Later series often followed a theme, like Series 34's coalmine theme and Series 23's tea party theme.
