Gillian Elizabeth Thomas (born 10 August 1953) is a Welsh actress, singer, and comedian. Early in her career she was known as Gillian Elisa Thomas.

Elisa was born in Carmarthen, Wales, and brought up in Lampeter;^[1] she began acting before she started school. As a sixth-former at Ysgol Gyfun Llanbedr-Pont Steffan in Lampeter, she co-wrote a Welsh-language musical, Yr Enfys (The Rainbow). After leaving school, she studied at the Welsh College of Music and Drama in Cardiff.

In 1975, she was chosen by producer Endaf Emlyn to play the lead in a Welsh-language rock opera.^[1] Since that time, she has been a well-known figure on Welsh-language television.

On S4C television, she played (1974–2010) the part of Sabrina Daniels in the long-running soap Pobol y Cwm^[2] and the comic character "Mrs O.T.T." in the variety entertainment programme Noson Lawen. She appeared in the gangster drama series Y Pris. She has performed one-woman comedy shows at the Edinburgh Festival. As a singer, she has completed three albums of new and traditional Welsh songs – Rhywbeth yn y Glas, Haul ar Nos Hir, and Lawr Y Lein, as well as appearing on a number of other recordings.

She is best known to English-speaking audiences for her leading role in the 2018 drama series Hidden, which was filmed in both Welsh and English,^[3] Elisa travelled around Wales with fellow actress Ruth Jones as part of the Welsh language show Iath Ar Daith, which shows celebrities learning the Welsh and putting it to practice.