Do You Need a Comma Before "Jr."?
Punctuation and Namesakes
Yesterday we celebrated Martin Luther King, Jr. Day in the United States. The official name has a comma before "Jr." The holiday was established in 1983 (See the document), and older style guides usually called for a comma before the "Jr." Most newer style guides, however, recommend omitting the comma.
When not struggling with holidays and their official names, 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.
Get more tips like this in The Grammar Devotional.
Disagree? Read more at Why Can't I Determine How My Name Is Spelled?