Spear are wildly effective weapons, in small-ish Combat Groups.
In particular, when used defensively, they can keep melee attackers at bay with no ability to retaliate relatively easily. You would, for example, be able to hold a 5ft-wide bridge against a mass of opponents pretty easily if they weren't willing to rush you and sacrifice themselves.
I was disappointed to find that in DnD 5e, they really aren't very effective or interesting weapons. They don't even have Reach.
I'm planning to come up with some ideas for a homebrew additions to them, and propose them on here, but before I do, are there any existing official ways to make a spear behave like this?