1825 Malachi Pickett and Miner Cox had a "frey" during which Malachi bit off part of the right ear of Miner. 
1840 Malekiah Pickett lived in District 851, Cobb County, Georgia in a household with males: 2 (Under 5), 1 (5 thru 9), 1 (10 thru 14), and 1 (30 thru 39); and females: 1 (Under 5), 1 (5 thru 9), and 1 (30 thru 39). 
1850 Maliza Pickett (age 50, born in South Carolina) lived in Baits Twp, Cobb County, Georgia, in a household with Mary Pickett (age 45), James Pickett (age 20), Malakah Pickett (age 16), James M Pickett (age 12), Rachel Pickett (age 18), and Elizabeth Pickett (age 16). Maliza Pickett was a farmer. 
1860 Mal Picket (age 33, born in North Carolina) lived in District 1003, Paulding County, Georgia, in a household with Mary Picket (age 60), Mal T Picket (age 25), Rochiel Picket (age 27), and Damoras Pace (age 21). Mal Picket was a farmer. 
1870 Malachi Pickett (age 68, born in North Carolina) lived in Burnt Hickory and Eutah, Paulding County, Georgia, in a household with Mary Pickett (age 70), William Pickett (age 7), Sarah Ferguson (age 30), and Jane Pickett (age 16). Malachi Pickett was a farmer. 
1880 Malachi Pickett (age 77, born in North Carolina, married) lived in Acorn Tree, Paulding County, Georgia, in a household with Rebecca M. Pickett (age 51), and Francis I. Pickett (age 14). Malachi Pickett's father was born in Virginia and his mother was born in Ireland. Malachi Pickett was a farmer. 
1886 Pvt Malachi Pickett died on April 8 and was buried at New Hope Cemetery, Paulding County, Georgia. Pvt Malachi Pickett was born in 1800.  
Private, Company A, 9th Battalion, Georgia Cavalry (State Guards), Confederate States Army
From a Pickett website no longer available:
Malachai Pickett, eldest son of Micajah Pickett and Susannah Johns, was born in 1803 in Rutherford county, North Carolina, probably on the property of his father along White Oak Creek. According to Malachai, his mother was born in Ireland. She lived with Micajah from about 1800 to his death in December, 1822, during which time he was legally separated from his wife, Kisannah, in Fairfield County, South Carolina. Susannah apparently was a widow; her maiden name is not known.
When Malachai was about three years old, his father moved to new lands in Green River Cove, northwestern Rutherford County, and from hence, when Malachai was between nine and twelve, to his large holdings on the North Fork Saluda River in Greenville County, South Carolina. Here Malachi first worked in his father's public house on the road over Saluda Gap, and then as an overseer on his father's plantation.
After Micajah's death in 1822, Malachai remained in Greenville County, South Carolina, until about 1834 or 1835, possibly hoping to obtain lands from the settlement of his father's estate. Under the settlement determined by the NC Supreme Court, however, all of the property not already devised was sold off, and Susannah Johns and her children received monetary settlement.
On legal documents, including Micajah's will, Susannah Johns and her children are referred to as "Pickett alias Johns", however, they referred to themselves as "Pickett", and never used "Johns" when they moved to other states.
Between about 1834 and 1840, Malachai migrated to northwest Georgia, settling in the sestern part of Cobb County, near New Hope Church and its small community. He had married his first wife, Mary (maiden name not known) in Greenville County, South Carolina, and his three eldest children were born there. It is not clear whether his fourth child, Malachai Thomas Pickett, was born in South Carolina or Georgia, since the move occurred about the time he was born. Censuses taken in subsequent years give both states as his birthplace.
By 1848, Malachai owned 180 acres along a tributary of Pumpkinvine Creek between New Hope Church and Lost Mountain community. This stream, on which he built a grist mill, became known as Pickett's Mill Creek", as it is to this day. This part of Cobb County, including New Hope, was transferred to Paulding County in 1851.
Within another two years, Malachai's eldest son, Benjamin W., established a separate household. Malachai began transferring his property along the Mill creek to Benjamin, except part interest in the mill, and, by 1860, owned a 240 acre farm further west in Paulding County, north of the village of Dallas. In 1864, he greatly enlargened his property by adding the "Gobler Glen Place" of 540 acres, purchased from John A. Jones. Malachai Thomas, his only remaining unmarried son by 1860, lived with Malachai and helped with the farm. The conditions of northwest Georgia were not very conducive to slave agriculture, and the Picketts of Paulding County were not slaveholders.
In 1861, Malachai Thomas (M. T., or "Mack") Pickett volunteered for Confederate service and was appointed an officer of the 19th Georgia Infantry Regiment. Benjamin W., who was a militia officer, was elected an officer of the 1st Georgia Cavalry, and James C. joined the 25th Georgia Infantry Battalion. Benjamin was killed 19 Sept. 1863, at the Battle of Chickamauga; the other two survived the war. During the summer of 1864, the War came even closer when part of the Union XX Army Corps crossed Pumpkinvine Creek just below the Pickett farm and marched past the Pickett house,advancing in the direction of Atlanta. On either side of Pickett's grist mill and along Pickett's Mill Creek, Union troops of O. O. Howard clashed with Patrick Cleburne's Confederate division in a short but extremely vicious battle. Sherman's advance was delayed for several days until he extended his flanks and maneuvered J. E. Johnston back into his next defensive line at Kennesaw Mountain. By the time of the Battle of Pickett's Mill, the grist mill was jointly owned by Benjamin Pickett's widow and J. C. Harris, to whom Malachi had sold his half interest in 1862.
After the War Between the States many years passed with little change in the structure of life in Paulding County, Georgia. This remained an area of white, small landowners, relatively isolated due to poor roads and lack of transportation. Situations and traditions changed very slowly. Malachai Pickett remained one of the more prosperous farmers in this district. His youngest son, Francis, died young in 1868, and his son M. T. married and eventually moved to Fulton County, Georgia, however, his second son, James C., remained in the area of New Hope and raised a large family.
Between 1870 and 1880, Malachai's first wife, Mary, died and Malachai remarried a younger woman named Matilda (maiden name not known). He died in 1886, probably in April, leaving eighty acres to his wife, with the remainder of his property to be equally divided among his heirs.
The graves of Malachai Pickett and his wives have not been located.
 Greenville County, South Carolina Deed, O-219, [FamilySearchImage], [FHLCatalog].
 United States Federal Census, 1840, [AncestryImage], [AncestryRecord].
 United States Federal Census, 1850, [AncestryRecord].
 United States Federal Census, 1860, [AncestryRecord].
 United States Federal Census, 1870, [AncestryRecord].
 United States Federal Census, 1880, [AncestryRecord].
 Find A Grave Memorial 41304165, [FindAGrave].
 Find A Grave Memorial at Ancestry.com, [AncestryRecord].