Roger Casamajor was born in 1976 at the Pyrenees. He started his acting studies in Andorra, and for five years he took part of Somhiteatre theater company, with which he travelled all over Catalunya, acting in plays like The Shawl by David Mamet or A Respectable Wedding by Bertold Brecht.
Roger moved to Barcelona to continue his studies, first at Col.legi del Teatre and then at Institut del Teatre, while he started his first works on films: El Mar by Agustí Villaronga (1999, Golden Bear nominee at Berlin Festival), Salvajes by Carlos Molinero (2000) or Guerreros by Daniel Calparsoro (2001), among others. After the conclusion of his acting studies, he focused completely in his actor career, working in a wide variety of movies, plays and TV movies and series.
Between 2000 and 2005 he shot L'Illa de l'Holandès by Sigfrid Monleón (2001), Nubes de Verano by Felipe Vega (2004), Amor Idiota by Ventura Pons (2004), Estrella del Sur by Luis Nieto (2002) or La casita blanca by Carles Balagué (2002). In theatre, he took part in El tinent d'Inishmore by Martin McDonagh (premiered at Teatre Nacional de Catalunya in 2003) and Some explicit polaroids by Mark Ravenhill (2000), both under the direction of Josep Maria Mestres. In TV, he participated in TV3 series Crims (2000), Temps de Silenci (2001), and Àngels / Sants (2005).
In 2006 he shot with Guillermo del Toro Pan's Labyrinth, winner of 3 Oscars and 7 Goyas. In the same year, he premiered Jo sóc un altre, directed by Tamzin Townsend at the TNC, and Carnaval by Jordi Galzeran, directed by Sergi Belbel at the Romea Theater. In TV, he participated in TV3's popular series Ventdelplà and Mar de Fons.
Between 2007 and 2009 he shot El coronel Macià by Josep Maria Forn, Bestezuelas by Carles Pastor, and international coproduction Henri IV by Jo Baier. In TV, he took part in TV3's series Via Augusta and Infidels.
In 2010 he worked again under the direction of Agustí Vilaronga in Pa Negre, winner of 9 Goyas and 13 Gaudí awards, including Best Actor for Roger Casamajor. In theater, he played La nit més freda, directed by Teresa Vilardell at TNC.
In 2011 he premiered La nostra classe by Tadeusz Slobodzianek, directed by Carme Portaceli at Grec Festival, and Pedra de Tartera by Maria Barbal, directed by Lurdes Barba at TNC. He also shot the tv movie Terra Baixa, by Isidre Ortiz.
In 2012 he premiered Els baixos fons by Maxim Gorki, directed by Albert Tolà and Carme Portaceli at the TNC. In TV, he participated in the serie Gran Nord on TV3.
In 2013 he took part in three theatre plays: Llibertat! by Santiago Rusiñol, and Dispara / Agafa Tresor / Repeteix, by Mark Ravenhill, both directed by Josep Maria Mestres; and Nerium Park, written and directed by Josep Maria Miró.
In 2014 he premiered Un enemic del poble, by Henrik Ibsen, under the direction of Miguel del Arco, at Teatre Lliure.
In 2015 he premiered L'art de la comèdia, by Eduardo de Filippo, directed and starred by Lluís Homar, at the TNC. It was the first of many plays with Homar: they met again in 2016 in El professor Bernhardi by Arthur Schintzler, and also in 2017 in Ricard III by William Shakespeare, both directed by Xavier Albertí at the TNC. He also shot the tv movies Fassman, by Joaquim Oristrell, and Laia, by Lluís Danés.
In 2017 Agustí Villaronga called him again for Incerta Glòria, winner of 8 Gaudí Awards. In TV, he took part of TV3 series Nit i dia and La Riera.
In 2018 he shot Todos lo saben under the direction of awarded iranian director Asghar Farhadi. In theatre, he participated in the musical play Maremar, an adaptation by Dagoll Dagom company of Shakespeare's Pericles, under the direction of Joan Lluís Bozzo. He also premiered Sol solet, by Àngel Guimerà, directed by Carlota Subirós at the TNC.
In 2019 he shot Netflix's tv serie Hache, under the direction of Jorge Torregrossa, and tv movie L'enigma Verdaguer, by Lluís Maria Güell.
In 2020 he shot the movies La Vampira de Barcelona, by Lluís Danés, with 14 nominations at the Gaudi Awards, and El ventre del mar, by Agustí Villaronga.
In 2021 he premiered Galatea, by Josep Maria de Sagarra, directed by Rafel Duran at the TNC, and shot the movies El fred que crema, by Santi Trullenque, and Tros, by Pau Calpe.