'Rahlff' is possibly derived from Wulf, or wolf. See discussion.
Hypothesis by Odd-Wiking Rahlff 2011-0605: Is it possibly from the place "Wulfen" on Fehmern? (http://de.wikipedia.org/wiki/Wulfen_(Fehmarn) , or does it derive from Radeleff <- Ratliff (English: variant of Ratcliff) <- Ratcliff? Meaning: English: habitational name from any of the places, in various parts of England, called Ratcliff(e), Radcliffe, Redcliff, or Radclive, all of which derive their names from Old English rēad ‘red' + clif ‘cliff', ‘slope', ‘riverbank'.
It seems that "Rahlf" was the original spelling ab. 1550. In 1702 the name gets an extra 'f' and becomes "Rahlff" in one branch.
John Kostick skriver i korrespondanse med Odd-Wiking Rahlff 110706: "On Fehmarn you will find both spellings of Rahlf/Rahlff they originate from the same family. The Rahlff family is often a more upper class family on the Island then the Rahlf family branch."
'In the above mentioned list of Fehmarn names - in the year of 1493 new clans are recorded by the families Lafrentzen [Lafrentz}, Kahlen [Kahl], Pechlins and Raleffen (Rahlff). The last one was dissolved by the authority in the year of 1504, because the cousins often lived in conflict; at times even had bloody battles, “weilen die Veddern in beständigem Streit leben, sich des öfteren auch blutig schlagen”.' (fra "The oldest families on island Fehmarn", http://www.fehmarngenealogy.com/the_oldest_families.htm )
As an example of how a "Fehmarn" ‘Sippe’ German for genealogy, can spread out from a small island far beyond the borders, over the oceans into other continents and from continent to continent. I want to write down at the end of this report the genealogy of the farmer, ship builder and trader families "Rahlff" spreading out from Gammendorf/Fehmarn to Denmark and Lemkenhafen/Fehmarn. It is to be mentioned that the name Rahlff, also Raleff or Radeleff appeared on the island Fehmarn already in the 15th century. When it was documented in a state archive in Copenhagen, Denmark, that on the 18th of March in 1488 a marriage was announced by the chamberlain (a sworn-in official of the island "Fehmarn" and witnessed by the church provost: "Johann Kule" in Landkirchen/Fehmarn between: Hans Houweschildt and Hans Junghes (his oldest daughter). Among the witnesses "Hinrik Raleff from Gammendorf" was documented.
The direct following lineage of the Rahlffs in Lemkenhafen starts later, in the beginning of the 17th century. With the:
1.) Olde Jörgen Rahlff in Gammendorf, birth and death not known. 1a.) His first wife Annecke birth not known, died in 1615 being struck by lightning.
2.) Jürgen Rahlff, property owner and chamberlain in Gammendorf/F. Born around 1610 there (acc. To Mannzahlregister) head of man registry. 2a.) Wife not registered. Etc. etc........>
The writing then continues with the genealogy of the Rahlff family of Lemkenhaufen. This information has been added to the database and can be requested.
(Kilde: The FEHMARN GENEALOGY Site http://www.fehmarngenealogy.com/lemkenha.htm )
Fordeling af navnet "Rahlff" i Tyskland: http://www.verwandt.de/karten/absolut/rahlff.html
og af "Rahlf": http://www.verwandt.de/karten/absolut/rahlf.html