You can blame this on Vince Keenan if you want to. He's the one who brought up The Liquidator. So the other day I started scanning some covers from the old men's action series books. I don't have my copies in any particular order. I don't even have the series together, so what I scanned is just a random sampling. The results are here, and you can watch a slideshow if you're so inclined. You've got your Stryker, your Striker, your Ryker, and even a vengeful merman. One of these days, if I get inspired again, I'll scan some more. And believe me, there are many more. Whatever happened to the guys who bought these things by the truckload?
Update: I've added about 20 more.