Two authors have written under the Tom Clancy name that I'm aware of, Mark Greaney and Grant Blackwood. the former considerably more prolific, Clancy himself is dead of course. Both of them have make no bones about their using the Clancy name and style and they do a good job of it.
I've a daughter who typically finds me the latest one for birthdays and Christmas, she usually gets them from Book Depository in the UK for a very good price and despite now being owned by Amazon they still ship free worldwide - how much longer, no idea.
- TheManFromPOST likes this