BUDDY BUDDY: Liu with co-star Jonny Lee Miller on the set of Elementary.
Jeffrey Neira/CBS

The pint-sized Liu is also accustomed to breaking barriers, a propensity that began in the early days of her career when she was cast as Alice in a production of Alice in Wonderland at the University of Michigan, where she graduated with a degree in Asian language and cultures. One of the first Chinese-­American actresses to make it big on the big screen, she’s surprised no one has made an issue of her ethnicity in playing Watson.

“I think that’s more of a hot topic,” she says. “Why are you putting an Asian person as Watson? People are harping more on the fact that it’s a woman, which I find fascinating.”

The daughter of Chinese immigrants who met in the U.S. while attending school, Liu grew up in Queens, N.Y., and graduated from Stuyvesant High School. Her parents, trained as a biochemist and a civil engineer, weren’t overly strict but did push their three children to excel academically. A self-described shy nerd, Liu says her mother recently sent her an envelope containing old report cards with comments from her teachers. “They pretty much all said, ‘She’s a sweet girl but she needs to communicate and participate in class,’ ” laughs Liu, the youn­gest of three siblings.

She eventually found her voice and passion for acting at the University of Michigan, where she transferred after attending New York University for a year. Her parents, however, were less than enthused by their daughter’s career choice. “Pursuing art as a career was an odd and uncomfortable issue for them,” she says. But it didn’t stop her from following her bliss.

After graduating in 1990, she returned to New York and hit the ground running, appearing in commercials, screen-testing for soap operas and volunteering as the “second, second assistant stage manager” at the Manhattan Theatre Club, where she absorbed as much as she could from watching rehearsals and asking advice from the actors. On an agent’s advice, she moved to Hollywood and began guest-starring on numerous television series, including The X-Files, NYPD Blue and ER. Her breakthrough role as the moody, hard-charging attorney Ling Woo on Ally ­McBeal is well documented: She first auditioned for the role of Nelle Porter, which went to Portia de Rossi, but executive ­producer David E. Kelley was so impressed by her that he created a new character for Liu, reportedly saying, “There’s no way we’re going to let that girl get away.”