These are probably “proof of burn” addresses.
The corresponding private key is unknown. If the private key was known, the public key hash would look much more random. By creating a non-random-looking public key hash, one proves that they almost certainly don’t know the corresponding private key. If nobody knows the private key, bitcoins sent there are effectively deleted.
Why would someone delete bitcoins? Well, for example, it’s one way to start up a new alt-coin. You can give people altcoins in exchange for deleting their bitcoins. Some people consider this more fair than giving out altcoins based on proof-of-work or random chance.