Walling
Most likely a medieval pet-name surname from Walter, though some writers also linked it to Wallingford and other place-names.
The #4,842 most common surname in the United States (2010 Census) — about 1 in every 42,439 Americans shares it.
Etymology
Historical surname writers most often treated Walling as a surname formed from Walter, via the old nicknames Wal, Wallin, or Wallon, with an added -ing ending. In that analysis, the final -g is simply an excrescent letter, not part of the core name. A minority of older writers instead connected it with place-names such as Wallingford or Wallington, but that explanation is less directly supported for the surname itself.
History
Bardsley and Harrison both group Walling with other Walter-derived forms such as Wallin and Wallon. Harrison also notes Wallingford, but that is best read as a separate place-name surname rather than the main source of Walling. In modern usage, Walling is relatively uncommon and appears chiefly in English-speaking countries, especially the United States and Britain.
Origin
Regions
Variant spellings
Fun fact
19th-century surname scholars often explained the extra -g in Walling as a spelling habit that crept in later, rather than a meaningful ending.
From the historical record
“WALLHAM, v. Walham, Welham. WALLING (Eng.) the A.-Sax. Wealing = Weal(h)'s Son [O.E. W{e)al[h, foreigner, Welshman -|- the fil. suff. -ing] occ. (A.-Fr.-Lat.) (with excresc. -g) for Waller), Wallin, Wallon, q.v. WALLING FORD (Eng.) Bel. to Wallingford (Berks), 13th cent. Waling{e)ford, A.-Sax. Welinga-ford…”
— Surnames of the United Kingdom: a concise etymological dictionary (2 vols in 1)