The name Thad has its origins in the Greek language, derived from the name Thaddaeus, which itself is a variant of the Aramaic name Taddai. This name can be traced back to the early Christian era, around the 1st century AD.

The name Thaddaeus is most notably associated with one of the Twelve Apostles of Jesus Christ, known as Jude Thaddaeus or Judas Thaddaeus. He is venerated as a saint in various Christian traditions. The name appears in the New Testament Gospels, particularly in the lists of the Apostles.

One of the earliest recorded individuals with the name Thaddaeus was the 4th-century bishop of Edessa, known as Thaddaeus of Edessa. He played a significant role in the early spread of Christianity in Mesopotamia.

In the 5th century, a monk named Thadde is mentioned in the writings of the historian Sozomen. He was known for his ascetic lifestyle and lived in a cave near Antioch.

During the Middle Ages, the name Thaddaeus appeared in various forms across Europe, including Taddeo in Italy, Tadeusz in Poland, and Tadeo in Spain. One notable figure was Taddeo Alderotti, an Italian physician and philosopher who lived in the 13th century.

In the 16th century, the English form of the name, Thad, emerged. One of the earliest recorded individuals with this spelling was Thad Roberts, an English clergyman and author who lived in the late 16th and early 17th centuries.

Other notable individuals named Thad throughout history include:

1. Thaddeus Kosciuszko (1746-1817), a Polish-Lithuanian military engineer and a hero of the American Revolutionary War.
2. Thaddeus Stevens (1792-1868), a prominent American political leader and abolitionist during the Civil War era.
3. Thaddeus Lowe (1832-1913), an American aeronaut and inventor who pioneered the use of balloons for military reconnaissance during the American Civil War.
4. Thaddeus Seymour (1829-1892), an American Civil War officer and Medal of Honor recipient.
5. Thaddeus Sobieski Coulincourt Lowe (1792-1849), an English-born American naval officer and explorer.

The name Thad has maintained a presence throughout history, particularly in the English-speaking world, and has been associated with notable figures across various fields, including politics, military, and exploration.