Here's an odder one: an E.Ludwig Victar 50mm f2.9.
When it comes to Ernst Ludwig, it's mostly the Tessar-type Meritar that you find in m42 mount. The Victar is what that lens replaced, being a triplet that was one of the standard lenses on K.W.'s Praktiflex SLR.
As the 40mm screw mount Praktiflex got replaced with the 42mm Contax & Praktica lines, Ludwig modified some of their 40mm lenses to fit those cameras via a non-removable m40 to m42 adapter. While m40 versions of the lens are hard to date — the Praktiflex was produced from 1939 to 1949, and I've never seen any serial number tables for Ludwig — the m42 versions are likely from the late '40s, which makes them suitable for this thread.
(It's possible that they continued production of this particular lens into the early '50s, but that seems less likely to me than simply repurposing otherwise obsolete stock.)
In my experience the m42 version of the lens is rarer than the m40, but not any more expensive.
This copy is rather fungus infested unfortunately, so it mostly just sits on a shelf as a decoration except when I dig it out for some soft-focus macro work.