Yes, the Kremlin.
Assange may have started out with pure intentions, but as he ran out of money, the only funding became available from the Kremlin. The cover for funding him was his show on RT, the Kremlin-funded English-language television station.
You might recall that Assange bragged about a huge dump of info about Putin and other Russian leaders/oligarchs that was soon to be dropped. It never did. It was either entirely BS from the start to provide cover, or existed but was withheld to keep happy his new sponsors.
You also may recall that the Wikileaks dumps of info stolen by Russian hackers on Hillary Clinton was miraculously released within hours of Trump's "I grabbed her by the pussy" tapes. A classic Russian disinformation move to distract the media, which was quite successful.
That's just glancing at a few highlights. By the time Wikileaks became significant, it was a straight-up Russian operation. It would have been a far better life decision for Assange to simply quit when he ran out of funds, than to sell out. Sad