Threlfall holds an MFA in acting from the Professional Actor Training Program at the University of Washington. He is also a member of Actors’ Equity Association (AEA), the Screen Actors' Guild/American Federation of Television and Radio Artists, the Screen Actors Guild, and the Stage Directors and Choreographers Society.
In his service at BYU, Threlfall has served as chair of the Music Dance Theatre program and was awarded the Randall L. Morgan Teaching and Mentoring Fellowship in August, 2008. In the fall of 2008, Tim was on sabbatical from the Theatre and Media Arts Department, putting the final touches on an acting textbook which he co-authored.
Prior to joining the faculty at BYU, Threlfall was the Artistic Director for the Seattle Civic Light Opera and the Northwest Summer Playhouse. He also served as Education Programs Coordinator for the Seattle Children's Theatre and spent three years in the resident AEA acting company of Seattle's Bathhouse Theatre.
Threlfall's professional career has included various directing and acting roles. In 2008, he directed Berlin, an original musical written by BYU alumnus Erik L. Orton. The production was filmed for viewing by BYU Broadcasting. It went on to receive the CINE Golden Eagle Award and a Rocky Mountain Emmy Award in October of 2009. Threlfall has directed twelve productions for the Tuacahn Center for the Arts, including its 2009 production of Disney's Aida and its 2014 production of The Wizard of Oz. In 2013 BYU produced The Phantom of the Opera, which Threlfall also directed. BYU was one of the first universities to put on the show, which has reached its 25th anniversary and has been shown over 100,000 times on Broadway. In 2015, he directed the premiere production of Frank Wildhorn's musical adaptation of The Count of Monte Cristo at BYU.
Threlfall's acting career includes numerous LDS Church films such as The Restoration, as well as in television and film projects shot locally, including the CBS series Touched By An Angel and the CW series Everwood. Also in 2009, Threlfall played the lead role of Aaron Young in One Good Man, a film directed by Christian Vuissa. In 2011, he played the part of Mr. Little in Thomas Russell's film Redemption: For Robbing the Dead. In 2014, Threlfall appeared in the web series project Beyond in the role of Reverend Pratt.
Threlfall published an article in The SDC (Stage Directors and Choreographers Journal) in the summer of 2013. The article, entitled "A Matter of Timing: Directing the Flood Effect at Tuacahn Amphitheatre," is Threlfall's second publication with the journal.
In 2015, he was appointed to the University Faculty Award Committee for an appointment of three years. The same year, he received funding from the college to present at the Theatre Educator’s Alliance International Conference.
Also in 2015, Threlfall and Gayle Lockwood made a presentation entitled "From Staged Reading to Rully Stages: Models for Academic Production of New Works" at the international conference of the Music Theatre Educator’s Alliance in Perth, Australia.
In 2017, Threlfall directed the first United States' adaptation of Stadium of Fire and was featured in the Daily Herald and BYU News.
- BYU News - BYU presents U.S. premiere of Chariots of Fire beginning Mar. 31 (30 March 2017)]
- The Daily Herald - Catch the U.S. premiere of 'Chariots of Fire' (30 March 2017)]
- BYU Radio Interview
- The Daily Herald - Caped nod: BYU brings 'Phantom of the Opera' to de Jong stage (17 Jan 2013)
- The Deseret News - BYU to stage epic musical 'Phantom of the Opera' (12 Jan 2013)
- The Universe - BYU to present 'The Phantom of the Opera' (11 Jan 2013)
- Y News - BYU will present full-stage production of 'Phantom of the Opera' (11 Jan 2013)
- Daily Herald - BYU offers early look at new ballpark musical (25 Mar. 2010)
- The Daily Herald: Warm-hearted family drama explores the pressures of LDS leadership (8 Oct. 2009)