Marc Álvarez is a composer working in theatre, dance and film. His credits include original music for Carmen, choreographed by Johan Inger and performed by companies including English National Ballet, Les Ballets de Monte-Carlo, Semperoper Ballett, Ballett Theater Basel, The Australian Ballet and Spain's Compañía Nacional de Danza. He also composed music for Inger's Don Juan, created for Aterballetto.
His theatre credits include Plataforma, directed by Calixto Bieito (a finalist for the 2008 Max Award for Best Music); El arte de la entrevista, written by Juan Mayorga and presented at Teatro María Guerrero; Peer Gynt, directed by Calixto Bieito for Teatre Grec; El Plan; Segismundos o el arte de ver for the Compañía Nacional de Teatro Clásico (CNTC); La Calderona (Audience Award at the Ciudad Rodrigo Festival); and El pintor de batallas. He has also served as musical director of Jesucristo Superstar and The Opera Locos, the latter winning the 2019 Max Award for Best Musical or Lyrical Production.

His work for dance also includes Prisma, choreographed by Iratxe Ansa and Igor Bacovich for Metamorphosis Dance; El salto de Nijinsky, choreographed by María Rovira for Trànsit Dansa (winner of the Butaca Award for Best Dance Production); and La niña farola, choreographed by Amaya Galeote for Ballet de Carmen Roche. His collaborations with Galeote also include Lego's, La incapacidad de exprimirte, Cookies on time and Destino/destino.
More recently, he has composed music for Los dos hidalgos de Verona, directed by Declan Donnellan; American Buffalo, directed by Ignasi Vidal; and Los Fugaces, written and directed by Denise Despeyroux.

In 2022, he received a New York Dance and Performance Award (Bessie) in the category of Outstanding Sound Design or Musical Composition for his musical arrangement work on Johan Inger's Carmen, performed by the Compañía Nacional de Danza at the Joyce Theater in New York.

His music has been featured in productions at venues including the Théâtre Mogador in Paris, the Semperoper in Dresden, the Joyce Theater in New York, Sadler's Wells in London, LG Arts Center Seoul, the Arena Sferisterio in Macerata, Teatro de la Maestranza, Teatros del Canal, Teatro de la Zarzuela, Teatre Grec and the Roman Theatre of Mérida, among others.