JavaScript is an interesting case, in that it was the only way to write code that would run in Netscape Navigator at the time. In a sense it had Netscape behind it, and then it had Microsoft behind it once they reverse-engineered an implementation for IE3.

I'm not very familiar with the history of Python, though it seems it was funded in its early years by various research institutes that employed Guido van Rossum, rather than a giant corporation.