Carl the Hedgehog is a wholesome 'chain' meme that gained massive popularity on Reddit in early 2019. Depicting a simple, pixelated hedgehog, the meme encourages users to share the image across various subreddits to simulate Carl's journey through the internet. Unlike many memes that rely on sarcasm or irony, Carl is built on community interaction, with users typically responding with a simple 'Hi, Carl!' in the comments. The meme eventually evolved into various scenarios, including Carl embarking on dangerous adventures or visiting niche interest groups, but the original spirit remains a lighthearted way for different online communities to interact through a shared digital traveler.