Zucker, CEO of NBC Universal, informed employees of his planned departure in a Friday e-mail, and Comcast executives said they wished him well.
A possible change-in-command has been looming since last December when Comcast Corp. agreed to buy a 51 percent stake in NBC Universal from General Electric Co.
Zucker said in an e-mail to NBC Universal staff that leaving was a tough decision. He made his name at NBC as a youthful executive producer of the "Today" show, then became its entertainment chief. He has been moving up the corporate ladder even as NBC's entertainment unit has faded.