Liam Ó Maonlaí (born 7 November 1964 in Dublin, Ireland) is an Irish musician best known as a member of the Hothouse Flowers. Ó Maonlaí formed the band in 1985 with his schoolmate Fiachna Ó Braonáin.

He attended Scoil Lorcáin and Coláiste Eoin, which is a Gaelscoil on Dublin's southside, although he credits his father as his main Irish language influence. He is a fluent speaker of Irish. He won an under 18 all-Ireland award for his skills on the Bodhrán. In 1985, he won the Irish music award known as Gradam Shlogadh along with Hothouse Flowers' bandmates. In 2005 he released a solo album entitled Rian which is a collection of tunes and songs in Irish Gaelic.

O' Maonlai also formed a band called The Complex in the early days with childhood friend Kevin Shields and drummer Colm Ó Cíosóig. After Liam left to form the Hothouse Flowers in 1984, Shields and O'Ciosoig were joined by vocalist Dave Conway and keyboardist Tina (who used no surname), and renamed themselves My Bloody Valentine, taking their name from a low-budget horror film.

Ó Maonlaí is also an active member of the Nuclear Free Future movement and contributed to the hosting of events in Carnsore and in Wexford Town in 2001. In 2004 he was a guest at the barefoot college which is located at Rajasthan, India. During his trip to India he played at the university in Jaipur along with some of the local musicians.