Gillian Pamela Horovitz (née Adams; born 7 June 1955) is an English female retired long-distance runner. She competed in the late 1970s and early 1980s in the women's marathon.
In June 1979, Adams finished second behind Joyce Smith at Sandbach in the British national marathon.
Adams won the 1980 Paris Marathon.
Adams married American screenwriter Israel Horovitz, in late 1981 and competed under her married name thereafter. She became the stepmother of Adam Horovitz of the Beastie Boys
Horovitz represented England in the marathon, at the 1998 Commonwealth Games in Kuala Lumpur, Malaysia.