Believe it or not, I've been playing Clicker Heroes of all games available.
I've kind of developed an interest for character grinding, as odd as it sounds; so, I was wondering if there's anything *here* that may do something similar in its own way.

The only games I know of here are the three Agarest: Generation of War titles. However, this doesn't mean the game has to have character levels for grinding. I can settle for repetitious looting for better and better goods as well.

Didn't want to mark this as a question, because there could be a variety of agreeable views.

Hammerwatch, Torchlight II, Terraria

The Elder Scrolls series, particularly Arena and Daggerfall.

Ultima 1-5

Wizardry 1-5 (except 4)

Might and Magic 1 and 2

Elminage Gothic

The original Bard's Tale trilogy

Edit: Added Ultima 4, 5 and Might and Magic 1, 2. Note that in Ultima 4, the most important grinding is to improve your virtues, as once you become the Avatar, it is really easy to get all the XP and Gold you'll ever need. (I actually suspect a certain exploit that requires being the Avatar was intentional.)

Note that later Might and Magic games aren't as suitable, as enemies don't generally respawn in 3-5, and respawns take a very long time later on.

This.

Also the Space Rangers series and if you really, really want to suffer, the X series.

This is the weirdest recommendation request ever.

Yes, ditto.

Defenders Quest

Not required, but grinding can help with Grim Dawn. Gotta get that rare loot.

I've played Diablo 3 WAY more than I think I should and it fits your needs.

I've heard pretty good stuff about Path of Exile, but never tried it myself.

From the options available here, I'd suggest Grim Dawn. Pretty fun game. :)

Terraria, Don't Starve, and The Escapists. All have daily grinds and repetition.

http://clickingbad.nullism.com/

Diablow II
Throne of Darkness
Space Hack

Loot until your brains liquify.

Can't believe no one has mentioned Rogue Legacy yet. That game is brilliant!

Diablo 2/3
Path of Exile