Ralf Jones is one of the playable characters since Metal Slug 6.
"OK, Let's get this done!!!" - Ralf's pet phrase
Though he is a colonel of his mercenary squad, his background is a complete mystery. Rumor has it that he came from a certain nation's special forces, or that he eradicated some secret society; Ralf shows no interest in such rumors. He does seem quite close to his commander, but no one has any clue as to how they met. He and Clark are brothers-in-arms, and they always go to battle together. He is known to participate in tournament fighting, and his close quarters combat ability far outstrips the average fighter. He is well known for his Vulcan Punch, a powerful salvo of punches powerful enough to kill infantry and destroy tanks. His most prized thing is a medal given to him by the president.
In Metal Slug 6 and Metal Slug 7, Ralf is most skilled with the melee attacks. Not only can his melee attacks cause double damage, he can also use his Vulcan Punch that can destroy even enemy tanks. Ralf is also able to withstand two shots instead of just one like the others (although they can get up if they landed on a special weapon upon receiving a standard ranged death). Ralf however can only carry half the ammunition for special weapons.
With the exception of Metal Slug Warriors, Ralf's appearances always have Nathalie Neo as a selectable character. Unlike in the main series, Ralf dies in one hit.
Originally as a cameo in the POW list, Ralf appears alongside Clark and Leona as purchasable units in a later update. His close range attack is doing his Vulcan Punch and he uses a Flame Shot for his long range attack. His special is the Galactica Phantom, a ramming single punch that bursts anything on flames upon contact, a move he uses in KOF tournaments.
In Metal Slug Attack, he's first available as a demonstration unit for the game's tutorial. He later becomes available as a $100 pre-acquisition unit. He later appeared in the Medal/VIP crank, and unit parts of him can now be purchased from the POW Rescue Shop. He also the one who turns the VIP crank. Once his skills are maxed out, his Galactic(a) Phantom produces four fireballs (similar to Jupiter King's) that are thrown in the air and damage enemy units further.
He also has an alternative version called Crazy Ralf, which is just a reskinned red Ralf with the Galactica Phantom as his long range move and his dive punch as his special move. Just like in Metal Slug 6 and 7/XX, he can revive once, if you max out his skills. Unfortunately, his illustration (based on his appearance in KOF XII/XIII) doesn't match his sprite, hence the confusion.
- For unknown reasons, Ralf and Clark are never randomly picked to be the possessed mini-boss during mission 5 of Metal Slug 6.
- Both Ralf and Clark originally appeared in the Ikari Warriors series. In the U.S. and European versions of Ikari Warriors, they were renamed Paul and Vince, respectively. They both also appeared in the The King of Fighters game series, under their original names.
- Ralf has also appeared in the games TNK III (his debut game) and its sequel Iron Tank'.
- Ralf's sprites are actually edited from Marco's. Fio confuses Ralf for Marco in King of Fighters Maximum Impact 2.
- He was named as Ralph Jones in Universal Metal Slug: Fierce Battle. He also uses Marco's death scream when killed.