I’m sorry to say that I’m not knowledgeable re: horoscope signs… I can link you to a post where @luthiluthi sorted a lot of them, so check that out…

Canonically, we have Word of God from the author re: birthdays for 3 of them:

• Lestat’s birthday is November 7, the birthday of Anne Rice’s late husband Stan (whom she partially modeled Lestat after).
• Louis’ birthday is October 4, which is Anne’s birthday.
• Claudia mentions her birthday in her diary (in QOTD) as being September 21, but she’s not sure if that’s really her birthday and her dads won’t explain it further (it’s probably the day she was turned, given the context of the diary entry). That’s Michele Rice’s birthday, Anne’s late daughter.

So that means (according to astrology-zodiac-signs.com, idk if it’s authoritative):

• Lestat’s a Scorpio – the most lusty/sexual sign, brave, passionate, stubborn, violent, jealous, secretive, resentful, manipulative ✓YEP
• Louis is a Libra – the scales, justice, contemplative, Cooperative,diplomatic, gracious, fair-minded, social, Indecisive, avoids confrontations, will carry a grudge, self-pity ✓YEP
• Claudia is a Virgo – a virgin, strong, practical, detail-oriented ✓YEP

There’s fanon that Armand’s birthday is Nov. 11 (@auburnandamberangel posted about it last yr, but I think it’s a fanon thing as well), and I like that it would be that close to Lestat’s on the calendar, another source of contention between them, that they’d share the same zodiac sign >;}

[^fanart by @garama]

Armand WOULD HATE following Lestat on the calendar, like, c’mon, Lestat would throw a HUGE BALL for himself (you KNOW he would), and then like 4 days later, Armand wants to have a big party… and everyone is like… ~Meh we just HAD one~… (They all went home already)(poor Armsy ;A;) 

So Louis suggests to Lestat that he share! And have a bday party for both of them in between, on like 11/9. And Lestat is all pouty like “WHY SHOULD I SHARE WHEN MINES FIRST?? 11/9 WILL BE TOO LATE FOR MINE”

^it’s a source of contention.

Anyone is welcome to add their thoughts, tho!