The juror made the remark about company CEO Isaac Larian during jury deliberations in the first phase of the federal trial in Riverside, said attorney Thomas Nolan, who represents MGA Entertainment Inc.
That phase ended on July 18 when jurors found the designer of Bratz characters conceived the idea for the dolls while working for Mattel.
The jury was considering possible damages during a separate proceeding that began Wednesday when the judge halted the case.
El Segundo-based Mattel said in a prepared statement it found the development to be "very unfortunate."
"This trial, however, has been, and will continue to be, about Mr. Larian's and MGA's wrongful behavior. Nothing changes that," the statement said.
The jury also ruled previously that Los Angeles-based MGA and Larian were liable for converting Mattel property for their own use and intentionally interfering with the contractual duties owed by the designer to Mattel.
Nolan said the dismissed juror, a woman, was dismissed after another member of the panel accused her of making inappropriate comments about Larian's ethnic background. He is Iranian.
"Today showed the best and the worst of the American system. One juror had a hidden bias, and another juror who took a solemn oath to be impartial had the courage to live up to that commitment," Nolan said.
Mattel, the maker of Barbie, filed the lawsuit against MGA, which began marketing the hugely popular Bratz line of sassy urban dolls in 2001.
Analysts estimate Bratz has made MGA more than $500 million a year.