Massive Stellar Collisions Could Explain Early Supermassive Black Holes
Dense stellar environments were common in the early Universe. These environments fostered more numerous stellar collisions, and some of those would've been mergers that formed very massive stars. Those stars would've exploded as supernovae, becoming massive black holes, the potential seeds for today's supermassive black holes.
We haven't written up this one. Universe Today has the full story — the link below goes straight to it.