Henry Crabgrass

 was a patch of crabgrass near Mollymauk Tealeaf's grave, who temporarily achieved sentience when Jester talked to them using Speak With Plants through the Charm of Plant Command. They were a cluster of crabgrass roots that encompassed a hive crabgrass mind.

Under the Speak With Plants spell that Jester cast through the Charm of Plant Command, Henry told the Mighty Nein that about 50 days prior, a small group of people came and dug up Mollymauk Tealeaf's body, and that there was "a lot of chanting" immediately afterward, but did not know what language it was because Henry does not know any languages.

Quotations

 * "Well, y'know, not all crabgrass is as cool as me." (when Jester comments on Henry's good memory)
 * "Ah, consent please." (when Jester first pets Henry)

Trivia

 * The cast started making jokes using Henry's voice and name, with Henry acting as an advocate for getting consent before snuggling — "Henry the Non-Grab-Ass Crabgrass" — or before reaching between someone's legs for an item. When Beau was insistent on trading journal entries with an Allowak's Sanctuary yeti but failed to persuade him, "Henry" piped up to say, "No means no."
 * Later, Veth advised Beau to remember Henry's guidance while dating Yasha.
 * Ashley Johnson dressed as Henry Crabgrass for the 2020 Halloween episode.
 * Sam Riegel's flask in was covered in a picture of grass with the words, "Hello! My name is Henry".
 * Matthew Mercer looked up the lifespan of crabgrass, which turns out to be a few weeks. If the Mighty Nein had returned to speak with him, as Laura Bailey says Jester would each year, they would find Henry's descendents in the area, with stories of their ancestor.