After the introduction of the Boeing 747 jumbo jet, Pan Am and Iran Air approached Boeing with a requirement for a variant that would have longer range for the New York to Tehran route, which at the time (early 1970s) was the longest commercial route in the world. At the same time, these airlines would accept an airliner with fewer passengers.
Boeing responded with the Boeing 747SP, which was shortened by 47 feet and had a taller tail and simplified flaps. The 747SP had a slightly higher speed and cruise ceiling than the normal 747 and could fly farther. Both airlines placed orders and the 747SP was inducted into service in 1976. Only 44 747SPs were built from 1974 to 1982, as it was rather a specialized version. Several were outfitted as VVIP aircraft, and one additional VVIP SP was built in 1987, for a final total of 45.
A number of other airlines operated small numbers of 747SPs over the years, but they have all been retired from commercial service. Two are still operated by Pratt & Whitney Canada for engine tests.
https://en.wikipedia.org/wiki/Boeing_747SP