Recorded in a wide range of recordings which seem to include Herreran, Herrevan, Herrieven, Horrovan and even Harraran, although this may be from Hanrahan, this is an Irish surname. According to the late Professor MacLysacht, the well known authority on Irish etymology, the derivation is from the ancient name O' hEararain, which seems reasonable. but he does not provide any examples or explanation as to how he arrived at this synopsis. If so then the meaning is believed to be "The son of the descendant of the dreaded one" from "earadh" meaning dread! MacLysacht does say, with which we concur, that the surname in any spelling is very rare, and it is said to be found only in County Donegal, and perhaps Derry. If this is the case it seems to share the same roots and basic history as O' Heron, an Oriel sept found in County Armagh, which as Harran anbd Herron is also recorded in Donegal. The problem in tracing many Irish surnames is that firstly most of the early registers of the country were destroyed in the Civil War of 1922, when the IRA burnt the Dublin Public Records office in a fit of vandalism, and secondly the total lack of education in mamy parts of the country until Victorian times. This lead to the development of large numbers of variant or "sounds like" surnames, which are very difficult to trace with accuracy.