You dare oppose me, mortal? refers to a popular image macro series, depicting distorted pictures of Thomas the Tank Engine.
It is primarily used online to joke about others disagreeing with someone.
The meme has a long lineage, as precursors image macros of Thomas the Tank Engine have been posted online since the early 2010’s.
The one image macro, that has been used on the “You dare oppose me, mortal?” meme was first used as an exploitable in 2014, later appearing in an earrape video in 2016.
“You dare oppose me, mortal?” was first posted on Reddit on April 17th, 2019, with captions making fun of math teachers reacting to students approaching a problem from a different angle.
The meme peaked in May, 2019, as the format would see reposts on subreddits like r/Dankmemes and r/memes as well as Twitter.
It would also appear on YouTube parodies, as well as DeviantArt artworks and humorous works.