Notes: This character was referred to as "Silver Surfer" only in solicitation text. In the comics themselves, & the Ultimate Secrets source book, he is called the Silver Searcher.
The Silver Searcher should also not be confused with the Silver Wings used by Gah Lak Tus in Ultimate Extinction (2006), which included a Silver Surfer that is NOT Norrin Radd. These are completely separate entities that Gah Lak Tus had apparently based on the Silver Searcher's physiology.
The Ultimate version of this character is not an alternate identity of the regular Marvel character as the Ultimate universe is a distinct reality.
See here for more information.