
Thomas Nast was born on September 27, 1840 in Landau, Germany. In 1846, his father Joseph Nast left Landau, enlisting on an American ship. He sent his wife and children to New York City, and at the end of his enlistment in 1850. Young Thomas Nast attended school in New York City from the age of six to fourteen. He was a poor student, but a very talented artist. In 1854, he was enrolled at the school of the National Academy of Design. In 1856, he started working Frank Leslie's Illustrated Newspaper. His drawings appeared for the first time in Harper's Weekly on March 19, 1859, as part of an article about police corruption.
In February 1860, he went to England for the New York Illustrated News to draw a prize fight between the American John C. Heenan and the English Thomas Sayers. A few months later, as an artist for The Illustrated London News, he joined Garibaldi in Italy. In February 1861, he returned to New York. In 1862, he became a staff illustrator for Harper's Weekly. In his first years with Harper's, Nast became known for sentimental subject matter, including his famous cartoon "Christmas Eve", penned in 1862, in which a wreath frames a scene of a soldier's praying wife and sleeping children at home. A second wreath frames the soldier seated by a campfire, gazing at small pictures of his loved ones. Another of his most famous cartoons was called "Compromise with the South", published in 1864, directed against those in the North who opposed the prosecution of the American Civil War. Nast's cartoons depicted themes in support of the Union cause during the war, and President Abraham Lincoln called Nast "our best recruiting sergeant".
After the war, Nast strongly opposed the Reconstruction policy of President Andrew Johnson. He depicted Johnson in a series of cartoons that mocked Johnson, depicting him as "King Andy". Other recurring themes in Nast's cartoons were racism and anti-Catholicism. Nast was baptized a Catholic. He converted to Protestantism prior to his marriage in 1861. Nast considered the Catholic Church as a threat to American values. When Tammany Hall proposed a new tax to support parochial Catholic schools, Nast was outraged. In a famous 1871 cartoon called "The American River Ganges," he depicted Catholic bishops, guided by Rome, as crocodiles moving in to attack American school children as Irish politicians. He viewed public support for religious education as a threat to democratic government. Nast favored nonsectarian public education.
Nast also drew anti-Irish themed cartoons. He depicting the Irish as violent drunks. He used Irish people as a symbol of mob violence, machine politics, and the exploitation of immigrants by political bosses. In the neighborhood in which he grew up, acts of violence by the Irish against black Americans were common sights. In 1863, Nast witnessed the New York City draft riots in which a mob composed mainly of Irish immigrants burned the Colored Orphan Asylum to the ground.
Nast's political cartoons were supportive of American Indians and Chinese Americans. He advocated the abolition of slavery, opposed racial segregation, and deplored the violence of the Ku Klux Klan. One of his more famous cartoons, entitled "Worse than Slavery," showed a despondent black family holding their dead child as a schoolhouse is destroyed by fire, as two members of the Ku Klux Klan and White League, paramilitary insurgent groups in the Reconstruction-era South, shake hands.

Nast's drawings were instrumental in the downfall of Boss Tweed, the powerful Tammany Hall leader. As commissioner of public works for New York City, Tweed led a ring that by 1870 had gained total control of the city's government, and had a majority of State Legislators in his pocket. Tweed and his associates Peter Barr Sweeny (park commissioner), Richard B. Connolly (controller of public expenditures), and Mayor A. Oakey Hall, defrauded the city of many millions of dollars. They accepted kickbacks by grossly inflating expenses paid to contractors. Nast published cartoons attacking Tammany corruption, focusing on the four principal players in 1870 and 1871. Tweed sent an emissary to offer Nast a bribe of $100,000, which was presented as a gift from a group of wealthy benefactors to enable Nast to study art in Europe. Nast pretended to be interested and he negotiated for more before finally refusing an offer of $500,000 with the words, "Well, I don't think I'll do it. I made up my mind not long ago to put some of those fellows behind the bars". Nast pressed his attack in the pages of Harper's, and the Tweet Ring was defeated in the election of November 7, 1871. Tweed was arrested in 1873 and convicted of fraud. When Tweed attempted to escape justice in December 1875 by fleeing to Cuba and from there to Spain, officials in Vigo, Spain, were able to identify the Tweed by using one of Nast's cartoons.
Harper's Weekly, and Nast, supported the re=election of Abraham Lincoln in 1864, and the election of Ulysses S. Grant in 1868 and Grant's re-election in 1872. In September 1864, Lincoln was running for re-election against Democratic candidate George B. McClellan, who positioned himself as the "peace candidate". Harper's Weekly published Nast's cartoon "Compromise with the South - Dedicated to the Chicago Convention". In it Nast criticized McClellan's peace platform as pro-South. Millions of copies were made and distributed nationwide, and Nast was later credited with aiding Lincoln's campaign.
Nast played important role during the presidential election in 1868. Ulysses S. Grant credited his victory to "the sword of Sheridan and the pencil of Thomas Nast." In the 1872 presidential campaign, Nast's ridicule of Horace Greeley's candidacy was especially severe. After Grant's victory in 1872, Mark Twain wrote the artist a letter saying: "Nast, you more than any other man have won a prodigious victory for Grant—I mean, rather, for Civilization and Progress." Nast became a close friend of President Grant and the two families shared regular dinners until Grant's death in 1885.
In 1873, Nast toured the United States as a lecturer and a sketch-artist. His lecture circuit made him a lot of money. He remained a staunch Republican and he supported Rutherford B. Hayes in the presidential election in 1876. Hayes later remarked that Nast was "the most powerful, single-handed aid I had". But Nast quickly became disillusioned with President Hayes and his policy of Southern pacification.
When the Weekly's publisher Fletcher Harper died in 1877, this resulted in a change in the relationship between Nast and his editor George William Curtis. Nast's cartoons appeared less frequently, and he was restricted in his ability to criticize Hayes or his policies. Nast and Curtis frequently differed on political matters and Curtis did not approve of Nast's cartoons assailing Republicans such as Carl Schurz and Charles Sumner who opposed policies of the Grant administration. Fletcher Harper had consistently supported Nast in his disputes with Curtis. After his death, his nephews, Joseph W. Harper Jr. and John Henry Harper, assumed control of the magazine and were more supportive of Curtis. Between 1877 and 1884, Nast's work appeared only sporadically in Harper's, which began publishing the milder political cartoons of William Allen Rogers.
During the presidential election of 1880, Nast felt that he could not support the Republican candidate, James A. Garfield, because of Garfield's involvement in the Crédit Mobilier scandal. He also did not wish to attack the Democratic candidate, Winfield Scott Hancock, his personal friend and a Union general who he respected. He submitted no cartoons to Harper's between the end of March 1883 and March 1, 1884, partly because of illness. In 1884, Curtis and Nast agreed that they could not support the Republican candidate James G. Blaine, a proponent of high tariffs and the spoils system, something that they perceived as corrupt. Instead, they supported Democratic candidate Grover Cleveland, whose platform of civil service reform appealed to them. Nast's cartoons helped Cleveland become the first Democrat to be elected President since 1856.
Nast's tenure at Harper's Weekly ended with his Christmas illustration of December 1886. In losing Nast, Harper's Weekly lost its political clout. Nast lost most of his fortune in 1884 after investing in a banking and brokerage firm operated by the swindler Ferdinand Ward. He returned to the lecture circuit in 1884 and 1887. In 1890, Nast published Thomas Nast's Christmas Drawings for the Human Race. He contributed cartoons in various publications, but was unable to regain his earlier popularity. Health problems, which included pain in his hands which had troubled him since the 1870s, affected his ability to work.

In 1892, he took control of a failing magazine, the New York Gazette, and renamed it Nast's Weekly. A Republican once again, Nast used the Weekly as a vehicle for his cartoons supporting Benjamin Harrison for president. The magazine had little impact and ceased publication seven months after it began. The failure of Nast's Weekly left Nast with few financial resources. He received a few commissions for oil paintings and drew book illustrations. In 1902, he applied for a job in the State Department, hoping to secure a consular position in western Europe. President Theodore Roosevelt was an admirer of the artist and offered him an appointment as the United States' Consul General to Guayaquil, Ecuador in South America. Nast accepted the position and traveled to Ecuador on July 1, 1902. During a subsequent yellow fever outbreak, Nast contracted the disease and died on the following December 7. His body was returned to the United States, where he was interred in the Woodlawn Cemetery in The Bronx, New York City.