The Big Bang Theory has a lot of characters, and despite many of them being your typical "nerds", they often have deeper, much more complicated personalities if you look below the surface. It seems somewhat ironic to try and determine their zodiac signs, considering astrology is something Sheldon ranted against in the show's very first episode, but each character actually ends up fitting surprisingly well with one sign or another.
If you're a diehard fan of TBBT or even just a casual watcher, you'll no doubt want to know which character from the show your zodiac most strongly aligns you with.
Aries: Beverly Hofstadter
Leonard's mother Beverly Hofstadter definitely matches the Aries sign best; she's the fiery, determined leader type, and she's very direct and to-the-point with her language. Other things that tie her to the Aries type are her fierce style as a mother and her penchant for accomplishment.
Taurus: Leslie Winkle
Experimental physicist Dr. Leslie Winkle is basically a female version of Leonard, but her personality is slighty different. She's practical and determined, but sets time aside for rest and relaxation.
While she can be a good friend at times, her quickly-changing emotions and overall ambition often get in the way of her relationships.
Gemini: Howard Wolowitz
Aerospace engineer Howard Wolowitz might be the most personable of The Big Bang Theory's four male leads. While he's just as nerdy as the rest of them, he's a little bit better at adapting to a social environment - a trait commonly associated with Gemini.
He's greatly intelligent and runs on curiosity, but his habit of jumping from thing to thing can make him unreliable at times.
Cancer: Bernadette Rostenkowski-Wolowitz
Microbiologist Bernadette Rostenkowski is a Cancer; she's intuitive and loyal to the end, and, because of this, she's very sensitive to the feelings of others - even if she doesn't always tell them that.
She can hop between stages of introversion and extroversion depending on her mood, and she's willing to make sacrifices to accomplish her dreams.
Leo: Debbie Wolowitz
Leo is a strong, passionate sign associated with powerful personalities. Debbie Wolowitz definitely falls in that category, as like a Leo she can be over-bearing at times but ultimately truly cares for others.
She sometimes has problems with self-assurance but will often try to be ambitious and decisive despite these.
Virgo: Amy Fowler
Neuroscientist Amy Fowler is a lot like Sheldon, but her unstoppable creativity and love for humanity actually align her with Virgo traits.
She's reliable and can be there for her friends, and her sensitive personality makes it easy for her to adapt to their interests.
Libra: Raj Koothrappali
Astrophysicist Raj Koothrappali is undeniably a Libra; he's tactful and fair, but can become too meticulous or idealistic at times. He enjoys social interaction somewhat, but his anxiety and lack and confidence often get the better of him when he's trying to make connections with others.
Some of the more positive traits that align him with the Libra sign are that he's very clever, is a good decision-maker, and has a very fashionable personality.
Scorpio: Emily Sweeney
A dermatologist with a quirky sense of humor that borders on macabre, Emily Sweeney is a Scorpio. Scorpios are known for their curious, secretive, and occasionally morbid personalities, but their loyalty and ambitiousness help them forge strong connections with others despite this. These are traits we see a lot in Emily, especially during her time dating Raj.
Sagittarius: Penny Hofstadter
Penny confirms she's a Sagittarius in the series' very first episode (leading to that famous argument with Sheldon about astrology).
Her personality traits actually line up rather well with this particular sign: she's naive and over-optimistic at times, but she has a strong mind and a level of optimism powerful enough to get her anywhere she wants to be.
Capricorn: Stuart Bloom
Talent artist and comic book shop owner Stuart Bloom is kind of a mixed bag, but he seems to fall in the Capricorn category - despite his low level of self-esteem, he's hard-working, creative, ambitious, and surprisingly devoted.
Like a Capricorn, he can be melancholy or over-dramatic at times, but he's also self-disciplined and has a clear idea of his goals in life, even if he doubts himself sometimes.
Aquarius: Sheldon Cooper
Sheldon is no doubt an Aquarius. His logical, no-nonsense mind and nerdy personality make him hard to relate to, but once he comes out of his shell he's surprisingly unpredictable.
He often takes to sarcasm when his point isn't coming across, and he doesn't like revealing his true emotions to anyone but his closest friends.
Pisces: Leonard Hofstadter
Despite being as much a nerd as Sheldon is, experimental physicist Leonard Hofstadter is more of a Pisces overall; he takes much less notice of others' shortcomings, choosing to compliment them when they get something right and help them out when they don't.
He can be very imaginative and enjoys some forms of escapist media, but he keeps himself confined to logic and won't go off into flights of fantasy.