Due to an extensive amount of interest in John Tanner, undoubtedly due to the recent movie, Treasure in Heaven: The John Tanner Story, I'll be posting a few items about John Tanner from time to time.
Here is a brief biography of John Tanner from the book Pioneers and Prominent Men of Utah (Frank Esshom, 1913, available here.) I hesitate to reproduce it, since some of the information is clearly false, and other information may be false, but I will footnote the information. Please leave comments if you have further, documented information.
TANNER, JOHN (son of Joshua Tanner and Thankful Tefft of New York). Born Aug. 15, 1778, Hopkinton, R. I.  Came to Utah Oct. 17, 1848, Amasa M. Lyman company. 
Married Tabitha Bently in Jan. 1800, Greenwich, N. Y. (daughter of Elisha Bently, pioneer Oct. 17, 1848, Amasa M. Lyman company ). She was born Aug. 23, 1780, died April 1, 1801. Only child: Elisha Bently b. March 23, 1801. 
Married Lydia Stewart in 1801 at Greenwich, Washington county, N. Y. (daughter of William Stewart and Amy Hunton ), who was born 1783.  Their children: William Stewart b. Oct. 27, 1802; Matilda b. Sept. 14, 1804, d. April 17, 1888; Willard b. Oct. 29, 1806, d. Aug. 12, 1807; Sidney b. April 1, 1809 (d. Dec. 5, 1895), m. Louisa Conlee; m. Julia Ann Shepherd; m. Rachel Neyman; John Joshua b. Dec. 19, 1811, d. Sept. 9, 1897; Romelia b. April 1, 1814, d. April 16, 1814; Nathan b. May 14, 1815; Edward b. Oct. 3, 1817, d. Oct. 21, 1817; Edwin (twin of Edward) b. Oct. 3, 1817, d. Oct. 8, 1817; Maria Louisa b. Nov. 28, 1818, m. Amasa M. Lyman (died); Martin Henry b. March 21, 1822; Albert Miles b. April 4, 1825, d. July 16, 1879. 
Married Eliza Beswick  1825, Bolton, Warren county, N. Y. (daughter of Everton Beswick and Anna Lamb), who was born Nov. 28, 1803, at Bolton, and died June 8, 1890, Payson, Utah.  Their children: Myron b. June 7, 1826; Seth Benjamin b. March 6, 1828; Freeman Everton b. Jan. 3, 1830; Joseph S. b. June 11, 1833, m. Elizabeth Haws; m. Jannette Hamilton; Philomelia b. March 10, 1835, d. May 28, 1838; David Dan b. Feb 8, 1838; Sariah b. July 19, 1849, d. March 12, 1853; Francis b. March 10, 1843, d. June 5, 1844.  Family home Payson, Utah. 
Notes to the Article
 So far, so good. These facts seem to be widely accepted, although they are probably from family sources and otherwise undocumented. Anyone have documentation? [See comment below and subsequent post here.]
 Amasa Lyman, the husband of John Tanner's daughter Maria Louisa, did travel in the company, but it was called the Willard Richards Company, and it reached Utah between October 10 and 19, 1848. Here is the record of the Willard Richards Company (1848) in the Mormon Pioneer Overland Travel database.
 Now this is a fascinating detail. I would almost dismiss this note out of hand, but an Elisha Bentley of unknown dates is listed in the same pioneer company as the Tanners. Is it possible that John Tanner's first father-in-law also joined the church and came across the plains with the family? He would have been very old at the time, and New Family Search shows his dates as 1730-1798. But it also shows his birthplace as Greenwich, Washington, New York, and that is false since Greenwich was not settled until the 1760s, so the birth and death dates could be false as well. But assuming that he was at least 20 years older than his daughter Tabitha, he would have been over 88 at the time that they crossed the plains. It's possible! It would be worth reading through all of the Sources about the pioneer company to see if there are any mentions of Elisha Bentley. Other options: it could be a brother of Tabitha Bently. It could be a cousin. Is it possible that this is John Tanner's son Elisha Bently Tanner? New Family Search shows Elisha Tanner dying March 11, 1858, in New York State, but like all the other dates about this family, that may need some double checking.
 This death date is contradicted in New Family Search, which shows a death date of April 9, 1801. It is hard to tell if this date is accurate, since there are pages and pages of sources for Tabitha, but none of them seem to be primary sources. As noted in footnote 3, Elisha Bently Tanner seemed to stay in New York.
 Lydia's mother is alternately listed as Amy Hulton and Hutton and Huntington.
 New Family Search shows Lydia's birth date as 1773 rather than 1783. Which is correct? I would guess 1783, because that would put her age at marriage at 17 or 18 to a 22 or 23 year old John Tanner, instead of being five years older than him, which was unlikely in that culture. She also had her last child in 1825, and it is much more likely that she was 41 at that time than that she was 51 at that time. It would be rare if a woman who started to bear children at a young age and continued bearing children regularly was fertile after her late 30s or early 40s.
 Although they may or may not be accurate, I'm not going to bother checking any of the children's dates, but I will note that these dates are a reminder how very difficult and tragic life could be back in the days before modern obstetrics and medical care: twelve children, with four of them dying before their first birthday, and then the mother dying eight weeks after the birth of her last child. Hopefully some of the joys of life compensated for all of the sad times.
 Was she commonly called Eliza? I've always seen her called Elizabeth in the family materials. I've never envied Elizabeth her job, marrying into a family with nine children, the oldest two years older than she was, the youngest still a baby, but from all accounts, she was an amazing woman.
 These facts are contradicted in New Family Search.
 As with Lydia's children, I will not bother checking the children's dates. They may or may not be accurate.
 John Tanner died April 13, 1850 in South Cottonwood (now Murray), Utah, and probably never traveled as far south as Payson, which was first settled in October 1850. The widow Elizabeth Beswick Tanner and some of her children lived there after they returned from the San Bernardino settlement in California, but John Tanner's children spanned the continent from New York and Massachusetts and Ohio to California. Here is a thorough summary of the lives of all his children by Karen Bray Keeley: Tanner Family Dispersion. Check out the rest of her wonderful site for more information about the family.