Dave Kelly, known for webcomics such as Purple Pussy, Living In Greytown, and his animations on Something Awful, also made a webcomic called Lizard. Unlike everything he's ever made ever, it didn't involve extreme profanity, massive violence, people getting killed off, or nudity. In fact, it was downright sickeningly sweet. In fact, Living In Greytown itself was made lighter and softer midway through the comic's life. The wacky vulgarity and silly deaths started being played for drama, and the comic was literally made lighter and softer by being drawn with pencils in bright soft colours, and culminating with a heartwarming ending.
Zeus And Sons is lighter and softer than the Greek mythology that it parodies, turning even the most horrible acts of the Greek gods into comical mishaps.
After several very dramatic arcs in a row, "New and Old Flames" is...well, something else entirely.
Grace's Birthday Party was full of genderbending hijinks after the mega-grimdark Painted Black arc. The writer doesn't like Darker and Edgier and doesn't find it fun to write, but drama begins to creep up, so its pretty cyclical.
Sinfest is a webcomic that used to be extremely cynical and celebrated the sinful lives of the main characters. Nowadays, the overall tone of the strip is very optimistic and deals with how the very human characters deal with the temptation of sin while exploring the connections they have with each other. It's hard to point out exactly where the shift occurred, but consensus says it became official during the Love Redeems storyline between one of the succubi and the nerdy bookworm. Earlier, it had God rejecting the notion of toning down his art work for this.
The alien trolls are violent, amoral, and unstable. In their previous incarnation they were peaceful, kind, and so weak they couldn't play the game that would create a new universe so they had to reboot it and be manipulated into something more aggressive.