Dr. Sal Kennedy is a long time friend of Tony Stark and Dr. Maya Hansen. The trio met at an emergent technology conference when Tony was in his early twenties.
Sal Kennedy is often sought out by Tony aka Iron Man for advice and guidance, aiding him through several crises. Sal eventually takes a position working for S.H.I.E.L.D. which at the time was under the leadership of Tony, despite his more hippy attitude toward such organizations.
Sal was killed when the S.H.I.E.L.D. Helicarrier came under attack by a genetically engineered neoplastic tumor. The attack that killed Sal was later revealed to have been arranged by the Mandarin.