Gloria and Francine want to know whether they need a comma in a name such as John Kennedy Jr. or Thurston Howell III?

You don't use commas in names that are followed by "Jr." or a numeral. If someone is referred to as "the third," you can use either the Roman numeral (III) or the Arabic numeral (3rd) after the name. When speaking a name, you say "the third"; but when writing a name, you don't include the word "the" before the numeral.

* Thurston Howell III
* Thurston Howell 3rd
* John Kennedy Jr.J