Comcast is a real-world Muggle telecommunications company. As a non-magical entity, it holds no place within the Wizarding world and is not mentioned in the primary canon of the Harry Potter series.
The term “Comcast” does not appear in any of the seven original Harry Potter novels by J.K. Rowling, nor is it mentioned in official supplementary materials such as Pottermore or author interviews. The Wizarding world largely eschews Muggle technology. Witches and wizards rely on magical means for communication and entertainment, such as the Owl Post, the Floo Network, Patronus messengers, and the Wizarding Wireless Network. Advanced Muggle technologies like television, computers, and the internet are generally absent from magical society. While Harry Potter's relatives, the Dursley family, were avid television watchers and owned a television set at Number Four, Privet Drive, the brand of their electronics is never specified in the books. Therefore, there is no canonical basis for an entry on Comcast within the context of the Harry Potter universe.