It's rare but sometimes comics come to an actual ending. I mean the loose ends are mostly tied together and the story comes to a close. Most comics just stop-- the writer or the artist get tired of it, etc.
Here are some that ended successfully.
Radioactive Panda: Sort of like Girl Genius but not so coherent a story and funnier. Seems to have died.
Dovecote Crest: Really good comic about Civil War reenactors that doesn't update enough. Also seems to have died.
Freakangels: The Midwich Cuckoos as grownups.
Dawn of Time: Strange little comic that takes place in the Jurassic? Triassic? Pleistocene? Who knows? Dinosaurs, Englishmen, mammoths and Sumerians coexist. Ended on a curious note. Maybe it will come back some day.
Our Time In Eden: Site 1. Site 2. Same guy that did Pictures of You.
Brat Halla: (RSS) When Thor and his brothers were teenagers.
Vex: sort of a high school coming of age story. With monsters and gypsies.
Digger: God death by Wombat. Very good. Surprisingly good.
User Friendly: Now it's just doing reruns.
Little White Mouse: story about this adolescent girl marooned on a station and what happens to her.
Indavo: Interesting SF comic.
Little Saiyalings: Curious little story by the guy that does Life on Forbez.
Anders Loves Maria: Swedish story about love, art and consequences. Beautiful ending.
Raising Hell: These guys were dysfunctional long before the zombies came along.
Twenty Sided Tale: Story of Lord of the Rings as a D & D game
Jack of All Blades: When dysfunction meets fantasy. Subsequently rebooted as Jacq of All Blades.
Buck Godot: Good science fiction strips are hard to find. A lot of the conventions of normal strips (romantic involvement, ultimate evil, etc.) don't seem to make the transition easily. Especially, funny SF strips. Buck Godot is an exception. He's also one of the rare fat slob heroes in any comic, SF or otherwise. Beloved by fellow fat slobs everywhere. I was sad to see it end. Someday, Phil might start again.
Marry Me: Pop Diva impulsively marries on stage and happens to marry a nice guy. Sabrina meets An Affair to Remember meets a Britney Spears with moral fiber. It's fiction, after all.
Narbonic: Unusual webcomic that actually has an ending. I think Narbonic might have been the sideways inspiration for Girl Genius.
Odysseus The Rebel: Terrific retelling of the Odyssey. But with the point of view that the Big O is rejecting the gods and is a reluctant participant.
Bite Me: This has my vote for a comedy film. Vampires in the French Revolution. I love it.
Minus: This one had a little girl as God. Sort of. She didn't act like God. No one viewed her as God. But she had those sorts of qualities. The strip had a curious ending.
Comedity: MPD Guy who builds bizarre toys. Including a robot girlfriend. Finally, MPD Guy decides he'd rather do something else.
Return to Sender: The comic is still there but the writer has moved on.
Rip and Terri: Terrorist assassin tries to make good and falls in love with schoolmarm hottie. Hilarity ensues.
rice boy : Truly strange little story.
Captain Excelsior: Dysfunctional super families are a lot of fun.
Strange Someone: Odd little werewolf story.
*You Damn Kid: Owen Dunne's take on childhood. Extremely funny but, sadly, Owen is leaving the world of webcomics. The archive is still up.
*The Beevnicks: Dunne's idea of a sitcom thriller. I really like the guy who suddenly gets lucky with twins afterwards looking like Moses must have done after witnessing the burning bush. Okay, that didn't come out right.
America Jr. Tiny U.S. Town Becomes Tiny Nation : Taken off line some time back. May be back, some day.
Anywhere But Here : Doonesbury meets Bloom County. But the author/artist hit a block.
Awakenings: One of the few comics about werewolves that I find interesting.
Spaghetti Strap Western: It's filtered. It must be good.