Steven Bochco, a celebrated television writer and producer whose sophisticated prime-time portrayals of gritty courtrooms and police station houses redefined television dramas and pushed the boundaries of onscreen vulgarity and nudity, died on Sunday in the Los Angeles neighborhood of Pacific Palisades. He was 74.

The cause was complications of cancer, a family spokesman said. He had received a stem cell transplant in October 2014 for leukemia.

Over three decades starting in the early 1980s, Mr. Bochco, whose earlier shows “Hill Street Blues” and “L.A. Law” upended the traditional hourlong drama, was one of Hollywood’s most prolific and sought-after producers. He mixed elements of daytime soap operas — like story lines that stretch over multiple episodes and feature a rich ensemble of characters — with a true-to-life visual style and colorful language.

The television and movie critic David Bianculli called Mr. Bochco “one of the most important figures in the history of television.” Mr. Bianculli, who has covered the entertainment industry for more than 40 years and runs the website TV Worth Watching, said on Sunday that television police dramas could be divided between those that came before and after “Hill Street Blues.”