In D&D 4e, can you move diagonally past:
- A solid object, like a wall?
- An enemy creature?
For example, can you move around a creature to the opposite side in two diagonal steps?
No, you can't move diagonally past a wall, but you can move past a solid object as long as it doesn't completely fill the corner (as in, you actually have room to slip past it). You could probably slip past a barrel, but not a crate filling its square.
Yes, you can move past an enemy creature diagonally, and thus move to their other side in two diagonal steps, as long as that creature doesn't completely fill their square. Naturally, doing so would normally trigger an opportunity attack since you're leaving a threatened square, but ordinarily this wouldn't prevent you doing it anyway.
From the PHB1, page 283:
That same page contains a diagram illustrating the limitation of moving around corners: it depicts a large and medium creature, both trying to move around walls, and they have to move such that the wall is completely out of their way - they don't just slip past the corner diagonally.