Every single pilot in the U-2 came from another airframe, but you probably knew that. Here's the backgrounds of the ~80 pilots we currently have in the U-2:
C-130 (including Coast Guard), EC-130, AC-130, C-17, C-5, C-21, C-12, KC-135, RC-135, B-52, B-1, F-14, F-15, F-15E, F-16, F-18 (Navy and Marine), FB-111, A-7, AV-8B, A-10, S-3, EA-6B, F-117, UH-1, MH-53, SH-60, CH-46, AH-1, T-34, T-45, T-37, T-6, T-38, T-3, USAF TPS grads, about a dozen with airline experience.
I'm 99.9% sure that Thunderbird 7 came out of the C-130 community. http://www.thunderbirds.acc.af.mil/07OfficerHTMS/7.htm