Chellas at a CFC Gala
Chellas was the co-creator with Ilana Frank and executive producer and head writer of the Canadian prime-time dramatic television series The Eleventh Hour, two-time winner of the Gemini Award for Best Series. Chellas and Tassie Cameron shared the Gemini for Best Writing in 2005 for the series finale, "Bumpy Cover". As well as being critically acclaimed, the series was nominated for over 30 other Geminis and won nine.
She adapted Linda Spalding’s Who Named the Knife into a television movie, Murder on Her Mind; she also executive produced. She wrote the script for Picture Claire, a low-budget feature directed by Bruce McDonald, that premiered at the Toronto International Film Festival in 2001. She also wrote The Life Before This, a low-budget feature directed by Jerry Ciccoritti that premiered at TIFF in 1999; she was also an associate producer. Her script for the Showtime/CBC television movie Restless Spirits (Canadian title: Dead Aviators) garnered her both a Gemini and a day-time Emmy nomination.
She has co-written two episodes of season 5 of Mad Men with Matthew Weiner. Both episodes, "Far Away Places" and "The Other Woman", were nominated for a Primetime Emmy Award for Outstanding Writing for a Drama Series. On February 17, 2013, "The Other Woman" won a WGA award for best episodic drama.
Chellas has directed four short films, three of which have premiered at The Toronto International Film Festival: Green Door (written by Barbara Gowdy; selected as one of Canada's Top Ten Short Films 2008 by TIFF); Trouser Accidents (included in the Best Canadian Short Films Showcase) and Three Stories From the End of Everything (nominated for a Genie Award for best live-action short); and One Tomato. She has published short fiction and interviews in Brick, Epoch, The Malahat Review and Grain. A non-fiction piece on embedded reporters, "Good to Go", appeared in The Walrus and The Commonwealth Journalists' Quarterly''.
Chellas was an Executive Producer on the Amazon series The Romanoffs. She wrote the episode Expectation starring Amanda Peet.
Her feature directorial debut was American Woman starring Hong Chau and Sarah Gadon. The screenplay was written by Chellas and she also produced the project, which premiered at Tribeca Film Festival in 2019. American Woman premiered as a gala presentation at the Toronto Film Festival in September 2019. Indiewire named Semi Chellas one of their 25 Rising Female Filmmakers to Know in 2019.
- Werlock, Abby H. P. (2001). Carol Shields's [sic] The stone diaries: a reader's guide. Continuum International Publishing Group. pp. 77–. ISBN 978-0-8264-5249-8. Retrieved 14 June 2011.
- "Archived copy". Archived from the original on 2012-07-21. Retrieved 2012-07-20.CS1 maint: archived copy as title (link)