The Bathroom is a multi-part animation created by A.M. Studios, a friend of the blog. We're not able to embed the videos, but since they're all NSFW that's not a huge problem. You can view them here.
Parts I and II contain muscle-and-hair-growth. Part III comes in two versions: one involves more muscle growth while the other transitions into a werewolf transformation.
Thanks again to Andréssaurio Rex for recommending issue 4 of this mini-series, where Bruce Banner transforms into a giant-size Hulk to clobber Godzilla.
Staying on the Godzilla theme, here is a Gozilla transformation motion-comic by Jextorz:
Thanks to Andréssaurio Rex and to Noodles on our Discord server for recommending this animation. The Marquis d'Urfé takes refuge in a family's home as they are attacked by vurdulak. The family falls victim to their infectious bite:
And on the topic of werewolf videos found on YouTube, here is the live-action short Freeway Werewolf, recommended by Marius on Discord:
Longtime readers know that I've posted a few times about this excellent animated short from 2014. I'm posting now to report that the film has been uploaded to Vimeo by its director, and is now fully accessible.
The story, in the words of the director: "Fabian is a shy, introverted teenager who lives with his bossy and prudish mother. Fabian's world gets turned upside down when he meets the fun and cool Felicia and they fall in love. But there is one small problem. Whenever the hormones rage in Fabian, he turns into a werewolf!"
There are three transformation scenes in the film, which I encourage you to watch all the way through. Technically the material is NSFW, but the film isn't prurient—it has something valuable to say about the harm of repressing one's "inner beast." Werewolf transformations have often been interpreted as a metaphors for various things: sexual maturation, out-of-control masculinity, and even erection and orgasm. Growing Pains successfully explores all of these metaphors, which makes it unique among werewolf films.
This "transformation-themed romantic comedy Visual Novel" by Jetyl has been released as a demo, and the final version is still underway. If you'd like to see a play-through, one has been posted to YouTube. I've cued it to the transformation scene (48:27):
Thanks to Bro43man for recommending this video, which he describes as "one of those scp anime stories about a haunted deer skull that forces normal people to try it on their head; it then transforms them into a wendigo-type monster."
Here is a group of various transformation videos found on the web, primarily from aspiring animators, though in one case the film is live action and in another the animators are professionals.
A suggestion from an anonymous commenter--an alien metamorphosis based on John Carpenter's The Thing:
From the same channel, a Hulk transformation:
Another werewolf, this time on a pirate ship! Thanks to Mike for suggesting it.
An anonymous commenter suggested the following animation, almost certainly by a professional. I have the feeling I've posted this before but I'm not entirely sure...
Here's the live action video, a homemade werewolf from episode 5 the web series "More Than Just Me," recommended by Ian Ricky: