Jackman speculates that Wilhelm was the son of Meinwerk [I], Thuringian count, whom he suggests married the sister of Hatheburg, first wife of Heinrich I King of Germany.
Graf in Südthüringau 949: "Otto…rex" donated property "in pago Thuringensi in comitatu Willilhelmi comitis…[et] in Gruoningo marcu quod idem Willihelmus comes et Gumberchtus fidelis noster" held previously to Kloster Hersfeld by charter dated 2 Feb 949. "Otto…rex" confirmed previous grants to Kloster Gandersheim including property "in pago Suththuringa in comitatu Uuillihelmi…[et] in pago Nordthuringa…in comitatu Theoderici in loco…Uuanzleua…[et] in Hliuthirithi in comitatu Irmenfridi" by charter dated 21 Apr 956. "Otto…rex" donated property "in Thuringia in comitatu Vuillihelmi" to Kloster Quedlinburg "pro filia nostra Mahthilda" by charter dated 956.
Graf im Gau Usiti [Husitin] 958: "Otto…rex" granted property "in locis Vurmerstat, Otunpach, Gozarstat, Haholtestat…in pago Usiti in comitatu comitis Uuillihelmi" to "vasallo comitisque…Billinc" by charter dated 2 Dec 958.
Graf im Altgau 961: "Otto…rex" granted property "Asundorf marcam et Dornsteti marcam Liubissa…in pago Hassigeuui in comitatu comitis Sigiuuridi…loco Biscopstat…in pago Altgeuui in comitatu comitis Uuillihelmi" to "vassallo Billing" by charter dated 23 Apr 961. "Otto…rex" granted property "predium quale Huodo in beneficium habet in pago Helmingouue in comitatu Willihelmi comitis…[et] predium quale Adalbertus comes habet in comitatu ipsius in pago Northuringorum" to Magdeburg St Moritz by charter dated 29 Jul 961.
The necrology of Fulda records the death "963 XVI Kal Mai" of "Willihelm com".
The name of Graf Wilhelm's wife is not known, although onomastics suggest a connection with families in Thuringia who used the name Poppo. Patze suggests that he married --- [im Grabfeld], daughter of Poppo [II] Duke of Thuringia, Graf im Volkfeld & his wife ---. Jackman comments that "this is chronologically very unlikely". The source which provides the basis for this suggestion has not been identified, although her naming her supposed son Poppo suggests a connection. It should be noted that the sons of Poppo [II] were Grafen im Grabfeld according to Europäische Stammtafeln.... 1
Research Notes: