Shandling filed a $100 million lawsuit charging that Grey had cheated him out of earnings from "The Larry Sanders Show." Zenga sued him demanding a screenwriter credit for the 2000 film "Scary Movie." Both have been settled.
Grey, a Hollywood talent manager at the time, said he was not involved in the details of either case. "Lawsuits were left to our attorneys," he told a Los Angeles jury.
Grey is among about 100 witnesses, including actors Sylvester Stallone and Farrah Fawcett and movie executives, called in the trial that has kept Hollywood buzzing for more than five years.
Neither Grey nor Fields, who will also testify later, have been charged.
Pellicano, 63, has pleaded not guilty to wiretapping the telephones of his clients' opponents and bribing police and telephone company officials to run illegal background checks on people including Shandling. He and four co-defendants are being tried on more than 100 federal charges.
The investigator who once worked for lawyers representing Tom Cruise, Elizabeth Taylor and Michael Jackson could spend the rest of his life in prison if convicted.
The two-week-old trial has revealed the seamy side of the movie industry. Pellicano has been accused of orchestrating smear campaigns and making threatening phone calls to help his rich and powerful clients.