I remember always being a little intimidated by MGM's Leo the Lion logo as a kid (big cat! the roar!) so whenever I see the roaring lion logo pop up these days, it always gives me a tinge of nostalgia that no other movie studio logo does for me. It's also the logo that has probably changed least over its nearly 100-year history.
Ethan Jones made another video showing the evolution of movie logos and this one focuses on Metro Goldwyn Mayer. Here is the fancy version that MGM uses today: