"Werewolf of London" is a 1935 horror film directed by Stuart Walker, notable for being the first feature-length werewolf movie. The story follows Wilfred Glendon, a botanist who travels to Tibet to find a rare plant called Mariphasa lumina lupina, believed to thrive under moonlight. After being bitten by a mysterious creature, he returns to London, where he discovers that the plant can temporarily alleviate his werewolf curse. As the full moon approaches, Glendon struggles with his transformations and the consequences of his actions.
You can stream Werewolf of London (1935) (1932) free and legally on OldReel, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.