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: