Ástþór joined Spindrift's Carroll: Berserkur as the Cheshire CatBorn and raised in Iceland's Vestmannaeyjar. Ástþór has performed with Vestmannaeyjar's Theatre Company, Kópavog's Theatre Company and graduated in 2007 from BA European Theatre Arts at Rose Bruford College in Greater London. 

From there Ástþór worked with independent theatre companies Bottlefed and Tangled Feet, worked closely with Theatre Delicatessen, and co-founded HalfCut in 2010. Their first major production Shelf-Life premiered fall 2012 and was received well. Ástþór has done voiceover work, fire-breathing as well as being a skilled musician.