Yes. After World War 2, surplus aircraft were cheap, plentiful, and offered great performance compared to pre-war designs, and many were converted to use as executive transports.
The A-26/B-26 was no exception, being the basis for the On Mark Marksman series. Some of the On Mark conversions involved pretty serious modifications like a new wing spar carrythrough and a new (and much uglier) cockpit.
The B-25, to my knowledge, had no comparable program carried out, but many became water bombers for use in fighting forest fires. There were undoubtedly some executive conversions made as well!
Other types like the Lockheed Hudson/Ventura/Lodestar transports and patrol aircraft were also popular conversion choices.