Astarion makes a cameo appearance in the 2024 Player's Handbook, but he appears to be in a spot of trouble. An illustration showcasing the Daylight spell features the Vampiric Rogue in the 2024 Player's Handbook. In the 2024 D&D rules, the daylight spell actually has the ability to harm vampires, although Astarion has temporary immunity to sunlight due to having an illithid tadpole embedded in his brain.
I reached out to the artist of the piece, David Astruga, who confirmed that it was indeed the beloved Baldur's Gate 3 character. "Indeed! it is Astarion," Astruga said via email. "I added him on my own from the sketch of that image, and the art directors thought it was fine to leave him there as a small easter egg for those who notice. It doesn’t have any further relevance, but it's good to remember that Astarion is a Wizards character, so he could obviously appear here or there."
While Baldur's Gate 3 was a major success for Dungeons & Dragons last year, the characters from that game won't make too many other appearances in the 2024/2025 Core Rulebooks, although the mind flayer on the alt-cover of the Monster Manual bears a strong resemblance to the Emperor (a romanceable mind flayer in Baldur's Gate 3.) When asked about the possibility of other Baldur's Gate 3 characters appearing in the Monster Manual, D&D art director Josh Herman told me "We're not going to see a ton of BG III stuff in the Monster Manual in general. It also came out late enough that we were in development pretty far on a lot of things. But the alt cover, that was also a good way for us to just show that this is all D&D."
However, Wizards is leaning heavily on Baldur's Gate 3 to promote its Project Sigil VTT project, utilizing both Astarion and Karlach in promotional art for the program and bringing in their respective voice actors Neil Newbon and Samantha Beart to play their characters in a D&D Live event at Gen Con in part to showcase Project Sigil.