The Thylacine or ‘Tasmanian tiger’ (Thylacinus cynocephalus), an iconic canid-like marsupial predator and last member of its taxonomic family (Thylacinidae) to have survived to modern times, was declared officially extinct in the early 1980s, half a century after the death of the last captive animal. However, the regularity and frequency of sightings of the species over more than eight decades since has not only created a zoological mystery, but also made it challenging to reconstruct the timeline of the fate of the species. To help resolve this intriguing historical-ecological problem, we compiled and curated a comprehensive inventory of documented sighting records from Tasmania from 1910 to 2019. By examining sources spanning official archives, published reports, museum collections, newspaper articles, microfilm, contemporary correspondence, private collections and other miscellaneous citations and testimony, we have amassed 1,223 unique Thylacine records from this period and resolved previous anomalies and duplications. Each observation in the database is dated, geo-tagged, categorised, quality-rated, referenced and linked to an image of its source material. Although purported observations have occurred every year, reporting rates vary across the decades in terms of frequency, type, location, and quality rating. Here we describe the database in detail, highlight its value for research, interpret the major patterns revealed by this archival compilation, and discuss the broader implications of the result of this work on the likely time and place of the Thylacine's extinction in the wild.