Oh, ok.
Then your obvious choice is a Ruger 10-22. It can handle everything from field mice to mountain goat to grizzly (shot placement!) to handling groups of armed marauders. Hmmm, can't carry it concealed, tho.....
Or is it a shotgun? loaded with the perfect shell for each application, of course.......except you can't conceal it. Snap! Wait, no problem, get the tax stamp for a super short shotgun! Oh, wait, now it's not a good duck or goose gun....
Actually, my tool analogy was perfect. Why? Because a gun, in truth, is also a tool. Like they said in Shop class, and it still holds true: "use the right tool for the job."
How many guns you "need" depends on how many different jobs you want to do.