Thaddius is a distinctive boys' name in United States, ranking #8372 in 1998 with 7 recorded births. The name reached its all-time peak in 2001 with 12 births ranking #5975. Since 1996, the popularity has increased by 16.7%. In 1998, approximately 1 in every 273,045 boys born was named Thaddius. FALLING Recent data shows the name is currently falling.