The Sukhoi Su-27 air superiority fighter was developed to meet the F-15 on equal terms

 The Su-27 was developed primarily for Russia's air-defense interceptor forces. Work on the T-10 design that led to the Su-27 began in 1969. The requirement was for a highly maneuverable fighter with very long range, heavy armament and modern sensors, capable of meeting the F-15 on equal terms. The first T-10 prototype (Western reporting name Flanker-A) flew in 1977. The early flight development programme revealed serious problems with initial design. Several pilots reportedly died during accidents testing these new aircraft. 

This led to a total redesign of the aircraft. The resulting T-10S-1 flew in 1981. The single-seat Su-27 (Flanker-B) eventually entered operational service in 1985 and despite its age remains a formidable interceptor. The Su-27 air superiority fighter and its variants have been exported to a number of countries and it is still widely used.

Its heavy armament of up to 10 air-to-air missiles gives excellent combat persistence; outstanding maneuverability, coupled with a helmet sight to cue agile R-73 missiles also make it a potent close combat fighter, and its large internal fuel capacity confers a very long range that allows the Su-27 to escort Su-24 interdictors.

All operators also use Su-27UB (Flanker-C) two-seat trainers. This retains full combat capability and has been developed further.

The Su-27K is a naval fighter variant that has the Russian naval aviation service designation Su-33 (Flanker-D). A total of 24 production aircraft has been built to date. The type made its first deployment on carrier Kuznetsov in 1995.

The Su-30 is a two-sear multi-role fighter. This aircraft is fitted with new avionics and has an added ground attack capability. It made its first flight in 1986. The Su-30 has been exported to a number of countries.

Sukhoi was developing variants for the reconnaissance and electronic warfare/command post roles. In 1988 Sukhoi flew a significantly developed single-seat version of the Su-27 as the Su-27M. This was proposed as a super agile Su-27 primarily for counter-air missions, but also with a greatly expanded air-to-surface capability. The Su-27M was later redesignated Su-35 by Sukhoi and offered as a MiG-29/Su-27 replacement. There was also a Su-37 pre-series/technology demonstrator aircraft. It was fitted with thrust-vectoring nozzles to confer even higher levels of maneuverability. This aircraft was actively proposed for the Russian Air Force, but received no production orders.

In the 1990s Russian signed an agreement with China, that allowed to build 200 Su-27SK aircraft from Russian-supplied kits. This aircraft is locally known as Shenyang J-11 and is referred in the West as Flanker B+. Its production began in 1998. However co-production of the basic J-11 was halted after around 100 aircraft were built. Some sources report that China violated agreement by installing indigenous electronics. It seems that Russia refused to supply kits for these aircraft to China. Then Chinese began to produce their indigenous versions of the Su-27, fitted with indigenous engines.