625, 5, 125, 25, 25, ?, 5

The answer is $\boxed{\text{25}}$.

The sequence is a list of numbers that are each one-fourth of the previous number. Therefore, the next number in the sequence is $\frac{1}{4} \times 25 = \boxed{25}$.

Option A, 5, is incorrect because it is not one-fourth of the previous number, 125.

Option B, 25, is correct because it is one-fourth of the previous number, 125.

Option C, 125, is incorrect because it is not one-fourth of the previous number, 25.

Option D, 625, is incorrect because it is not one-fourth of the previous number, 25.