Parodied in Eyebeam; the eponymous character is written out, and his "actor" is so upset that he leaves the strip. Patrick Duffy then fills in for two strips as "Eyebeam".
Parodied in an issue of Scooby-Doo Team-Up. Mystery Inc. drops in on the version of the Teen Titans from Teen Titans Go! and not only does the Gang comment on Robin's Art Evolution (where he changes from looking like how he was in the old Scooby-Doo Movies series and Super Friends series to the TTG! look), but also his voice. Fred chalks it up to a person acting differently towards his friends than they do with a grown-up.
Frank Kelly Freas was the most prominent cover artist in The '50s. After he left, Norman Mingo took over primary cover art duty, although a few other artists chipped in from time to time. Following Mingo's death, the cover duties rotated more frequently, although Richard Williams eventually became the most prominent of the bunch in The '80s. They then rotated very frequently until Mark Fredrickson took over primary cover duties in The New '10s.
Antonio Prohías, the original artist of Spy vs. Spy, handed the art duties over to Bob Clarke, then George Woodbridge for one issue, and finally Dave Manak before the strip fell into the hands of Peter Kuper in 1997. During Clarke's tenure, the gags were usually written by Don "Duck" Edwing, while Michael Gallagher and Andrew J. Schwartzberg were the most prominent gag writers during Manak's tenure. Kuper usually writes his own gags, although other artists have chipped in from time to time.
"Celebrity Cause-of-Death Betting Odds" was originally illustrated by Thomas Fluharty, but after he left the magazine, Hermann Mejia took over. However, James Warhola drew two installments, and Jon Weiman handled them for a four-issue stretch (interestingly, he only had one other contribution to the magazine overall) before Meija returned. The installment was later retired, but brought back again with Sam Viviano (under the alias Jack Syracuse) handling the art. It's also no longer written by Mike Snider, who stopped contributing to the magazine over Executive Meddling.
The comic Monroe and... was originally drawn by Bill Wray, but after it ended, it briefly returned with Tom Fowler as the artist.
For their parodies of the first six installments of the Star Wars franchise, the parody of A New Hope was drawn by Harry North, Esq. and written by Dick DeBartolo with help from Nick Meglin. The next four in line had only DeBartolo writing and Mort Drucker illustrating, but the parody of Revenge of the Sith instead went with Hermann Meija drawing and David Shayne writing.
Happens in-universe in V for Vendetta when Lewis Prothero goes catatonic and can no longer play the voice of the supercomputer Fate. As the pretense had been that the voice on the radio really was the computer itself talking, replacing him credibly proves problematic.
In Batman '66, a comic series set in the continuity of the Batman TV show with close actor likenesses, Catwoman is depicted in different stories as either Julie Newmar's version or Eartha Kitt's. Similarly Mr. Freeze appears as his George Sanders version in his first appearance and as the Otto Preminger version later on. No explanation is given in the comics for the characters' radical changes in appearance.
Generally speaking, many long-running comic book characters change their appearances over time as different artists come and go - usually without any explanation given in-universe, befitting the trope. A couple random examples include Alfred Pennyworth, Batman's butler, who went from short and chubby to tall and skinny, and the recurring Superman villain Mr. Mxyzptlk, whose appearance also changed over time