A sex doll (also love doll or blowup doll) is a type of anthropomorphic sex toy in the size and shape of a sexual partner. The sex doll may consist of an entire body, or just a head, pelvis, or other body part (vagina, anus, mouth, penis, breasts) intended for sexual stimulation. The parts sometimes vibrate and may be moveable and interchangeable. Sex dolls exist in many forms, but are usually distinguished from sex robots, which are anthropomorphic creations designed to be able to engage in more complex interactions.

Some of the first sex dolls were created by French (dame de voyage) and Spanish (dama de viaje) sailors in the sixteenth century who would be isolated during long voyages. These masturbatory dolls were often made of sewn cloth or old clothes and were a direct predecessor to today's sex dolls. Later, the Dutch sold some of these dolls to Japanese people during the Rangaku period, and the term "Dutch wives" is still sometimes used in Japan to refer to sex dolls.

One of the earliest recorded appearances of manufactured sex dolls dates to 1908, in Iwan Bloch's The Sexual Life of Our Time. Bloch wrote:

In this connection, we may refer to fornicatory acts affected with artificial imitations of the human body, or of individual parts of that body. There exist true Vaucansons in this province of pornographic technology, clever mechanics who, from rubber and other plastic materials, prepare entire male or female bodies, which, as hommes or dames de voyage, subserve fornicatory purposes. More especially are the genital organs represented in a manner true to nature. Even the secretion of Bartholin's glands is imitated, by means of a "pneumatic tube" filled with oil. Similarly, by means of fluid and suitable apparatus, the ejaculation of the semen is imitated. Such artificial human beings are actually offered for sale in the catalog of certain manufacturers of "Parisian rubber articles."

In 1918, Austrian artist Oskar Kokoschka commissioned a life-sized doll of Alma Mahler (whom Kokoschka was in love with) to German puppet maker Hermine Moos, while he was in Dresden. Although intended to simulate Alma and receive his affection, the "Alma doll" did not satisfy Kokoschka and he destroyed it during a party.

German surrealist artist Hans Bellmer has been described as “the father figure of the modern sex doll” for his sex puppets in the 1930s whose more realistic models moved sex dolls further into the future. Bellmer made three dolls, increasingly sophisticated in design, which also made waves in the international art community.

A report that, as part of the Borghild Project, Nazi Germany made sex dolls for soldiers during World War II has not been verified by reliable sources and is now considered to be a hoax. It is however said that the commercial sex doll has its origins in Germany, especially since the creation of the Bild Lilli doll in the 1950s, which was in turn the inspiration for creating the famous Barbie doll.

The production of human simulacra to substitute for human sexual partners took several technological leaps forward in the late twentieth century. By the 1970s, vinyl, latex and silicone had become the materials most frequently used in the manufacture of sex dolls; silicone, in particular, allowed a greater degree of realism.

A 1982 attempt to import a consignment of sex dolls into Britain had the unintended consequence of ending the law against importing "obscene or indecent" items that were not illegal to sell within the UK. Having had the dolls seized by Her Majesty's Customs and Excise officers, David Sullivan's Conegate Ltd. took the case all the way to the European Court of Justice, and won in 1987. Britain was forced to lift its stringent import prohibitions dating from 1876 because for imports from within the European Community they constituted a barrier to free trade under the terms of the Treaty of Rome.

Shin Takagi, founder of the company Trottla, manufactures lifelike child sex dolls in the belief that doing so provides a safe and legal outlet for men expressing pedophilic desires. This has been disputed by paraphilia researcher Dr. Peter J. Fagan, who argues that contact with the products would likely have a reinforcing effect, increasing the risk of pedophilic action being taken. Since 2013, Australian officials have confiscated imported shipments of juvenile sex dolls legally classified as child exploitation material..

Sales of sex dolls increased significantly during the COVID-19 pandemic.