I wonder which ONE surname is featured most prominently across Jin Yong universe?
Suppose the only way to find out is to count the number of explicitly surnamed characters of the major surnames.
Let's try to compile a list for a couple of names.
Chen - Chen Xuanfeng, Chen Jialuo, Chen Jinnan, DGSD Elder Chen.... I'm sure there are others.
Huang - Huang Yaoshi, Huang Rong, Huang Shang, Huang Rihua (...just kidding, he is a big part of wuxia though, but not quite in novel context )
Xu - Xu Tianhong, (Elder) Xu Chongxiao... others?
Wu - (Elder) Wu Changfeng, Wu Sangui...
Zhang - Zhang Cuishan, Zhang Sanfeng, Zhang Wuji, Zhang San, Zhang
Duan - Duan Zhengming, Duan Yanqing, Duan Tiande, Duan Zhixin (Yideng), Duan Yu, Duan Zhengchun
Mei - Mei Niansheng, Mei Fanggu, Mei Wenxin (Mei Fanggu's mother), Mei Chaofeng
Feel free to contribute to the list.