Some argue that there were multiple Reformations in the 16th-century. What were the major ideas and who were the major figures in the Protestant Reformation, the Radical Reformation, and the Catholic Counter-Reformation?

Indeed, there were several reformations within The Protestant Reformation. The reverberations of Martin Luther's act of dissent -- the posting of the 95 Theses on the door of Wittenberg Cathedral in 1517 -- helped to create additional denominations, including the Baptist faith and Calvinism.
Martin Luther is the most important figure in the protest that characterized The Protestant Reformation. His grievances against the Catholic Church included, not only their corruption, but also their insistence on followers heeding the Church's interpretation of Scripture. Martin Luther believed that everyone ought to have access to the Bible, to interpret its meaning for themselves. His ideas coincided with the creation of the printing press (invented in the mid-fifteenth century). The Lutheran faith is named after him and inspired by his beliefs.
Another key element of the Lutheran faith is the absence of pomp and circumstance in houses of worship. Lutheran churches, unlike Catholic churches, were defined by simplicity: wooden pews for the worshipers, and a wooden pulpit for the clergyman. No icons were displayed; no ornamentation, such as painted windows, was to distract a worshiper from the work of studying Scripture.
John Calvin succeeded Martin Luther as the most prominent Protestant reformer. He was a law student in France when he joined the Protestant effort, becoming a theologian in 1536. It is from him that we get the notion of predestination -- the idea that everything is determined by God's will, including who will and will not enter Heaven.
Calvin also encouraged a strong work ethic. It is, possibly, from Calvinist faith that we get the proverb, "Idle hands do the devil's work." Certainly, this principle is an element of Protestant faith. Calvinists were marked by their commitment to discipline, frugality, and hard work.
The Catholic Reformation began with the Council of Trent (1545-1563). Also called, The Counter-Reformation, it was a direct response to The Protestant Reformation. The Church had alas agreed to internal reform. They would dedicate themselves to pursuits that would be more beneficial to the public. Out of this commitment, the Jesuit Order was born. The order was founded by St. Ignatius of Loyola, a priest, a Spanish knight, and a theologian, who was committed to charitable works, missionary work, and education. 
https://www.biography.com/religious-figure/john-calvin