John Cleese is a hugely respected memeber of any cast he is in. The actor has been working for decades now, and he has the abillty to turn up in some pretty unexpected places as well.
Speaking of, if his Twitter is to be believed, it looks like he might turn up in the DCEU too. As spotted by Twitter user Dennis Lamb (via ComicBook.com), the Batman v Superman UK twitter account and photographer Clay Enos, who has worked on both Batman v Superman and Suicide Squad recently started following the actor.
This is hardly any sort of confirmation, but it is made interesting by the fact that Joe Manganiello involvement in Ben Affleck's the Batman movie was pegged thanks to people realising he started following people and accounts related to the DCEU.
Again, this is a little tenuous, but there is some precedent, and it certainly is weird to see. While miles away from a confirmation, its enough for a raised eyebrow I reckon.