Halldór Smárason is an Icelandic composer and pianist. His music has been performed in Iceland, across Europe and in the United States by ensembles including the Iceland Symphony Orchestra, Ensemble intercontemporain, Caput and the Siggi String Quartet, with whom he has collaborated extensively. His work has also been presented at festivals including ManiFeste in Paris and Nordic Music Days.

His work often draws on stories, memories and personal experiences, with a particular focus on harmony, timbre and musical narrative. His debut portrait album, STARA, was released by Sono Luminus in 2020 and features the Siggi String Quartet and guests. His music has also appeared on recordings by Sæunn Thorsteinsdóttir and Herdís Anna Jónasdóttir.

Alongside composing, Halldór performs regularly as a pianist and keyboard player. He studied composition at the Iceland University of the Arts and Manhattan School of Music as a Fulbright scholar, and later studied with Beat Furrer in Graz. He has received artist salaries from the Icelandic state, a residency at Civitella Ranieri and several nominations for the Icelandic Music Awards.