  This review describes the most common theories behind long-duration gamma-ray
burst progenitors. I discuss two astrophysical scenarios: the collapsar and the
magnetar models. According to their requirements, the progenitor should be an
envelope-free massive star with a fast rotating, collapsing iron core. Such an
object, called a TWUIN star, may be produced by chemically homogeneous
evolution either from a massive single star or a massive binary system. Various
outcomes of this evolutionary path (e.g. supernova explosions and gravitational
wave production) are also mentioned, and directions for future research are
suggested. In the era of multi-messenger astronomy, my hope is to present a
timely overview on how stellar astrophysicists are searching for progenitor
models of long-duration gamma-ray bursts, and what they have found so far.
