Contra and Castlevania are one of the Konami popular series.They refer each sometimes and they are bundled together with frequency side by side.
In Contra: Hard Corps in stage 3 before break the first door climb the wall,you will meet a strange character,he will ask you if you want to do money in the Arena,respond yes and you will enter the to the Arena.The first boss you will fight is a parody from both Simon Belmont and Simon Masoto.The theme that will play in the background will be SIMON 1994RD.
Konami Collector's Series: Castlevania & ContraEdit
Three Castlevania and two Contra games were bundled together for the PC in Konami Collector's Series: Castlevania & Contra.
The second game in Konami's "ReBirth" series made for WiiWare. It was later followed up with Castlevania: The Adventure ReBirth