The most prevelant variations based on frequency numbers:

Hurlburt, Hulbert (frequency numbers to be added)

An alphabetic list of some Possible "Hurlbut" Variations ( not counting possible double vowel or double "t" combinations, or vowels inserted between the "l" and 'b") thanks to D. Michael Iradi:

Harlbad Herlbad Hirlbad Horlbad Hurlbad

Harlbard Herlbard Hirlbard Horlbard Hurlbard

Harlbart Herlbart Hirlbart Horlbart Hurlbart

Harlbat Herlbat Hirlbat Horlbat Hurlbat

Harlbed Herlbed Hirlbed Horlbed Hurlbed

Harlberd Herlberd Hirlberd Horlberd Hurlberd

Harlbert Herlbert Hirlbert Horlbert Hurlbert

Harlbet Herlbet Hirlbet Horlbet Hurlbet

Harlbid Herlbid Hirlbid Horlbid Hurlbid

Harlbird Herlbird Hirlbird Horlbird Hurlbird

Harlbirt Herlbirt Hirlbirt Horlbirt Hurlbirt

Harlbit Herlbit Hirlbit Horlbit Hurlbit

Harlbod Herlbod Hirlbod Horlbod Hurlbod

Harlbord Herlbord Hirlbord Horlbord Hurlbord

Harlbort Herlbort Hirlbort Horlbort Hurlbort

Harlbot Herlbot Hirlbot Horlbot Hurlbot

Harlbud Herlbud Hirlbud Horlbud Hurlbud

Harlburd Herlburd Hirlburd Horlburd Hurlburd

Harlburt Herlburt Hirlburt Horlburt Hurlburt

Harlbut Herlbut Hirlbut Horlbut Hurlbut

An alphabetic list of some Possible " Hulbert /Hulburd " Variations. Again thanks to D. Michael Iradi:

Halbard Helbart Hilbert Holbert Hulbart

Halbart Helberd Hilbird Holbird Hulberd

Halberd Helbert Hilbirt Holbirt Hulbert

Halbert Helbird Hilbord Holbord Hulbird

Halbird Helbirt Hilbort Holbort Hulbirt

Halbirt Helbord Hilburd Holburd Hulbord

Halbord Helbort Hilburt Holburt Hulbort

Halbort Helburd Hobart Holiberd Hulburd

Halbourt Helburt Hobert Holibird Hulburt

Halburd Hilbard Holbard Hubbard Hurlbutt

Halburt Hilbart Holbart Hubbert

Helbard Hilberd Holberd Hulbard

Summary of the two main immigrant from D. Michael Iradi:

The descendants of the MA immigrant Thomas HURLBUT(T) and Sarah (Nye?) have generally guarded the spelling “Hurlbut(t)/Hurlbu(r)t” throughout the first several generations. However, further on down their line, many seem to have adopted the spelling “Hulbert/Hulburt,” similar to that of the line of William Hulburd I, immigrant to CT. I think the reason for this, is because there are a lot of English (i.e. Anglo-Saxon/Germanic) forenames that already end in "bert," and it just "sounded good/better/more normal" (e.g. Albert, Dilbert, Dagobert, Engelbert, Filbert, Gilbert, Hubert, Humbert, Lambert, Robert, Wigbert, etc.) but there are not many personal names in English that end in "but" (e.g. halibut.…)

By contrast, the descendants of William HULBURD/HULBERT I the immigrant have absolutely wild fluctuations in spelling, however as a rule of thumb, an “r” does not generally appear before the “l” in their surname variations as with the descendants of Thomas Hurlbut(t) indicating a possible different etymology for their surname. Any reference to the line of William Hulburd I in CT as “Hurlbut/Hurlburt” is apparently revision by modern writers who have confused the two lines with each other (almost certainly due to their misplaced reliance on the falsified works connecting the two lines, which are fabrications by notorious genealogical con-artist “Gustav Anjou.”) However, it should be noted that the descendants of William Hulburd I were occasionally referred to by clerks/scribes in NJ as “Hubbard,” and in MA and PA as "Hurlburt", and these surname variations may have already possibly been applied to the Hulburds in Ct as well.

An etymology from “Hurlbat” (from the bat used in the game of hurling) may apparently be possible only for Thomas’ line. In contrast, an etymology of either “Halberd” (from the weapon/town official), or the original Anglo-Saxon forename HOLDBEORHT (meaning Gracious and Bright) – probably the latter – may be indicated for William Hulburd I’s line.

The HALBERT families of VA, the Carolinas, etc. are apparently the descendants of a William Halbert (b.1681 in Eng.) who immigrated to VA sometime bef. his marriage to Mary Cook (widow of Thomas Wood) of VA. They were m. bef. 10 Feb 1708. Their descendants are also quite numerous.

Another family found throughout the south/VA in the 1800’s and later is the HELBURT/HELBURT Family, which is also extensive today. They are probably related to the aforementioned Halberts, or possibly the Holberts below.

The HOLBERT/HOLBURT Family, likewise, is quite numerous today. They may be a VA family, as the earliest with that name seem to be in VA, including a Michael Holbert who was born about 1760 in Loudown, VA. Also, a William Holbert was born in Connecticut in 1755 (although some say Holland) and settled in Montague Township, Sussex County, N.J. on the banks of the Delaware River in 1770. He afterward purchased a large tract of land in Lackawaxen, Pike County, Pa. extending from the confluence of the Delaware River to Mast Hope. Here he had large lumber interests and his farm was the oldest in that locality. His name appears on the assessment roll of Lackawaxen Township as having 2 mills showing he was an enterprising man. The descendants of this William Holbert are primarily in the South.

The HILBERT family seems concentrated around Ohio to Indiana to Michigan, and also VA, also in the 1800’s. The name is apparently German in origin, and likely originates with George Adam Hilbert (b.1710 in the Palatine, Germany), immigrant to PA. The Hilbert descendants are very numerous.

The HUBBARD Family is descended from the various immigrants, including: 1. George Hubbard (d.18 Mar 1685, immigrant 1633 to CT); or 2. James Hubbard (b. 14 Aug 1603 d. 26 Apr. 1639 in Watertown, MA); or 3. William Hubbard (b.1591 d.19 Aug 1670 in Ipswich, MA). Their descendants are extensive. Also, Daniel, the grandson of John Hulburd I of Northampton , MA (son of William Hulburd I, immigrant to CT in 1630), apparently changed the spelling of his surname to "Hubbard", as his descendants remain known to this day.

Those of the HOBART/HOBERT family are apparently all descended from the immigrant Edmund Hobart (b.c.1570 d. 8 Mar 1646 in MA).

The HUBBERT Family, prominent in TN and Alabama, and also in the Midwest, are apparently descended from the immigrant Colonel James Hubbert (b. 18 Jul 1741 in Eng. d. 8 Feb 1824 in Warren Co., TN), and his descendants (and former slaves who adopted his surname?) are very numerous.

As per the descendants of William Hulburd I immigrant to CT in 1630, other records of the time show various members of the family with the surname spelled as “Halburd/Halbert,” and later on even "Holbert", but there is no evidence that earlier generations actually signed their own names as such, and so these should be considered as other examples of clerical variations in spelling “Hulburd.”

According to a Jeremy Hulbert of Co. Norfolk UK in 1999 : “…There are early records of the name "Hulbert" as a Norman surname imported by the successful invasion of England in 1066….The earliest document showing our surname that I know of is dated 1168 and refers to HOLBERTUS VENATOR (is this “old man Hulbert?”) There is also mention of a JOHN HOLDEBERT in a document dated 1205….I think that the Wiltshire Hulberts' family name derives either from the Norman line or from before the Norman invasion as the original Anglo-Saxon (sic. Germanic) name HOLDBEORHT (meaning Gracious and Bright). Other Hulbert family names probably did derive form local prowess as HURLBATS on the hurling field, but village hurl-batters were less likely to have their names recorded in documents (because they were not landed aristocracy – DMI). Consequently, we are left with records only from the noble or landowning HULBERTS or those with official positions in politics, local government or religious organizations….”