Base (named after the Base 1 and Base 2 stages from Contra, in which the song plays), is a track written by Hidenori Maezawa, and one of the most familiar tracks among the series.
- Contra — Base 1 and Base 2.
- Contra 4 — An arrangement of the song appears in the third level of the game, although it is fairly different from its first version.
- The composition has been sampled by the Filipino band Parokya ni Edgar in their song "Bagsakan".
-  — The song, as it appears on the original NES game.
-  — The song, as it appears on the arcade version of the game.
-  — The heavily revamped arrangement written by Jake Kaufman for Contra 4.