William Smead Jr.'s mother, Judith Stoughton Denman Smead, was the widow of John Denman, and had two children, John Denman Jr. and Mary Denman, when she married William Smead, Sr. (date unknown).
William, his mother, Judith, and half sister, Mary Denman, emigrated to the Massachusetts Bay Colony with Winthrop's Fleet on the ship John and Mary in 1630.  William's father had already died or may have emigrated with them and died soon after. Note: Author Meredith Colket says the family emigrated in 1639. (The year of Judith's death.). 
William's half brother, John Denman, emigrated separately to Bermuda in 1635, later coming to the Colonies)
The following family members are listed as sailing with the 1630 Winthrop's Fleet:
Smead, ____ From Coggeshall, Essex. No further record. Probably died soon after arrival at Massachusetts Bay Colony.
Smead, Judith; Wife of ____Smead. Sister of Israel Stoughton (Savage).
Smead, William; Son of Mrs. Judith Smead (Savage).
Stoughton, Israel (settled at Dorchester, Massachusetts Bay Colony) From Coggeshall, Essex. Opposed Massachusetts Bay Colony Governor John Winthrop's rule and was disfranchised for writing an heretical book. Returned to England and fought under Cromwell in the Civil War, with the rank of Lieutenant Colonel in Rainsborough's regiment. (Savage). He died in 1644 at Lincoln, Lincolnshire, England.
Stoughton, Elizabeth; Wife of Israel.
Stoughton, Thomas (settled at Dorchester, Massachusetts Bay Colony); From Coggeshall, Essex. Brother of Israel. Constable on September 28, 1630. On October 19, 1630, applied to become a Freeman (M.C.R., Volume I, page 80); made a Freeman on 18 May 1631 (M.C.R., page 366). In 1635, Thomas Stoughton married Mrs. Margaret Huntington, widow of Simon Huntington. Moved from Dorcester, Massachusetts Bay Colony to Windsor, Connecticut Colony where he died in 1642.
Stoughton, _____; Wife of Thomas (Savage).
The family then settled in Salem, Essex county, Massachusetts Bay Colony. William's mother died in 1639 and he was mentioned in her Will. . Judith Stoughton Demman Smead's Will divided her estate among her three children: "John Denman, Mary Denman, "wife to Clement Maxfield," and WIlliam Smeed." 
The History of Deerfield, Massachusetts contains the following entry:
"On the death of his mother, [William Smead Jr.] was put under the care of John Pope; Pope died [on] April 12, 1646, leaving by will 'vnto William Smead my Little boy my Loomes and such tacklings as do belong vnto them which is to vallew of 3 pounds provided he be willing to Learn my Trad, and that there be a comfortable Agreement mad between them afterwards.' [It is not known h]ow much William [Smead Jr.] . . . benefited [from] this conditional bequest . . ., but he is found in Northampton and was made [a] freeman [there] in 1660; in 1671 he bought house lot No. 25; his name does not otherwise appear [at Northampton, Massachusetts Bay Colony] before Philip's War, but he became one of the early permanent settlers; he died before 1704." 
On December 31, 1658, William Smead Jr. married Elizabeth Lawrence (1642 - 1704) at Dorchester, Massachusetts Bay Colony. They had 10 children.
William Smead Jr. served in King Philip's War and participated in the Falls Fight under Capt. Turner in 1676. 
On May 19, 1680, he was listed as a "freeman" and living in Massachusetts Bay Colony. 
William Smead Jr died on January 1, 1703, in Deerfield, Massachusetts, at the age of 73. His wife and three daughters (Waitstill Smead Warner, Mehitable Smead Hull Nims, and Thankful Smead Hawks) died a year later as a result of the February 29, 1704, Deerfield Raid or Massacre. 
Mehitable Hull Smead Nims, born on January 2, 1667, first married Jeremiah Hull, then married Godfrey Nims on June 27, 1692; captured from Deerfield in the raid of February 29, 1704 and died on the forced march to Canada. 
Samuel Smead ,1669 - 1731; his wife, Mary Price, and their children died in a cellar during the Deerfield Raid. Samuel Smead married Mary Weld in 1707. 
John Smead, born on August 27, 1670; died in infancy. 
John Smead, born on August 27, 1673. John Smead received bullet wound in Meadow Fight after the February 29, 1704, Deerfield Raid.  In 1720, John Smead and Anna Weld married. Subsequently, John Smead and Abigail Weld married.
Waitstill Smead Warner, born on March 5, 1679. On January 5, 1698-9, Waitstill Smead and Ebenezer Warner married. Waitstill Smead Warner was captured from Deerfield in the raid on February 29, 1704, and died on march to Canada. 
↑ 12.012.1 History of Deerfield, Genealogies, page 302.
Peter Wilson Coldham. The Complete Book of Emigrants: A Comprehensive Listing Compiled from English Public Records of Those Who Took Ship to the Americas for Political, Religious, and Economic Reasons; of Those Who Were Deported for Vagrancy, Roguery, or Non-Conformity; and of Those Who Were Sold to Labour in the New Colonies. Baltimore: Genealogical Publishing Co. 1607-1660. 1988. Page 167.
Massachusetts, Compiled Census and Census Substitutes Index, 1790-1890. Ancestry.com Operations Inc., Provo, Utah, USA. 1999. Original data: Jackson, Ron V., Accelerated Indexing Systems (AIS), comp.. Massachusetts Census, 1790-1890. Compiled and digitized by Mr. Jackson and AIS from microfilmed schedules of the U.S. Federal Decennial Census, territorial/state censuses, and/or census substitutes.
Massachusetts, Town and Vital Records, 1620-1988 Publication: Name: Ancestry.com Operations, Inc.; Location: Provo, UT, USA; Date: 2011;
"New England Ship and Passenger Lists." In Boulder Genealogical Society Quarterly (Boulder, CO). Vol. 4:2 (May 1972), pp. 27-30 (1630), p 29.
New England Marriages Prior to 1700 [database on-line]. Provo, UT, USA: Ancestry.com Operations Inc, 2012. Original data: Torrey, Clarence A. New England Marriages Prior to 1700. Baltimore, MD, USA: Genealogical Publishing Co., 2004.
Soldiers in King Philip's war. Containing lists of the soldiers of Massachusetts Colony, who served in the Indian war of 1675-1677. With sketches of the principal officers, and copies of ancient documents and records relating to the war, by George Madison Bodge, 1841-1914, Published 1891. https://archive.org/stream/soldiersinkingph00bodg#page/206/mode/2up
Suffolk County Wills; Author: McGhan, Judith; Probate Place: Plymouth, Massachusetts, Ancestry.com. Massachusetts, Wills and Probate Records, 1635-1991 [database on-line]. Provo, UT, USA: Ancestry.com Operations, Inc., 2015. Original data: Massachusetts County, District and Probate Courts.
Winthrop Fleet of 1630, The: an Account of the Vessels, the Voyage, the Passengers and Their English Homes, from Original Authorities, by Charles Edward Banks; Boston: Houghton Mifflin, 1930. 119p. Reprinted by Genealogical Publishing Co., Baltimore, 1961. Repr. 1983. Reprinted 2003. Pages 92 - 93. http://files.usgwarchives.net/ma/mastate/winthropfleet.txt