If you own the movie on physical media or are streaming it, English subtitles are typically built-in.
If you have a digital file (like an .MKV or .MP4) and need an external subtitle file (.SRT), several reputable repositories host them. Note that you may need to choose a file that matches your specific version (Theatrical vs. Director’s Cut) to ensure the timing is correct. Donnie Darko subtitles English
: Highly recommended for its clean interface and extensive movie database. If you own the movie on physical media
The 4K UHD release includes English SDH (Subtitles for the Deaf and Hard-of-Hearing) for both the theatrical and director's cuts. Director’s Cut) to ensure the timing is correct
* Presentation: Widescreen 2.35:1/16x9. * Audio: English Dolby Digital 5.1. English Dolby Surround 2.0. French Dolby Surround 2.0. DVD Movie Guide Donnie Darko [4K UHD] (2001) - DVD Movie Guide