8. Figure 2 is the three views of a geometric solid. Then the volume of the solid is $\qquad$

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8. $\frac{4}{3}$.

From the three views, we can determine that the geometric body is a triangular pyramid $P-ABC$, as shown in Figure 3.

From the top view, we know that plane $PAB \perp$ plane $ABC$, $AC = BC$, $OC = 2$, and $OA = OB = 1$.

From the left view, we know that $OP \perp AB$, and thus, $OP \perp$ plane $ABC$, and $OC \perp AB$.

From the front view, we know that $OP = OC = 2$. Therefore, $V_{\text{triangular pyramid } P-ABC} = \frac{1}{3} S_{\triangle ABC} \cdot OP$ $= \frac{1}{6} AB \cdot OC \cdot OP = \frac{4}{3}$.