The older the internet gets, the more it's like a city that keeps building on top of its own ruins. What's is your favorite bit of internet archeology if memes are like artifacts and relics?
An early Slashdot meme: Can you Imagine a Beowulf Cluster of These (usually about things other than computers).
Searching Slashdot comments seems hard now that search engines aren't what they used to be, but I found a post referencing the by then pre-existing meme from the 14th of July, 2001: https://hardware.slashdot.org/story/01/07/14/0748215/Can-You-Imagine-a-Beowulf-Cluster-of-These
This was probably one of my earliest exposures to Internet joke memes (before they were commonly in image form).
Of course, in Dawkin's original sense, any knowledge passed from human to human is a meme, so if we are being hyper-literal about it, I'd say it's actually how to talk - we all may have mutant variants of the meme and some may have multiple copies (multilingual), but without have caught some variant of that meme, no one would achieve much! But to meet the 'dead' part, I guess it would have to be a dead variant of the meme (possibly still and ancestor of modern languages). Proto-Indo-European is one such (although hard to choose just one).