Clark Still is one of the playable characters since Metal Slug 6.
"Hey, Come on!!" -Clark's pet phrase.
It seems that he joined the mercenary squad some years ago, but nothing else is known about Clark other than that. He and Ralf have long been brothers-in-arms, and they always go to battle together. Just like Ralf, there are also countless rumors about his past, and they are all equally outlandish. However, the very number of these rumors and the known fact that he often joins Ralf in tournament fights offer a clue to his fighting prowess. On the battlefield his combat style somewhat differs from Ralf's, but he shows expertise in close quarters combat techniques all the same. Enemies unfortunate enough to run into him find themselves instantly flung into the air and crashing back down.
In Metal Slug 6 and Metal Slug 7, Clark is the most balanced character, having average stats on everything. Clark is also able to use his Argentine Backbreaker on common enemies, and he will be temporarily invincible after each hit. If he use it in succession, the points will be multiplied, allowing for very high scores.
- His favorite food is oatmeal.
- 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.
- Clark's sprite are actually edited sprites of Tarma.
- He is known as Clark Steel in old KOF games.
- In Metal Slug Defense, since he can't use his Argentine Backbreaker on enemies, he opts for hurling an explosive barrel, this special ability is called "Nageppanashi S.A.B.".
- Clark is the only character, thus far, to have temporary invincibility from a unique ability.
- Clark, Fio, Red Eye and Alisa are the only playable characters who wear a cap, with Clark being the only male playable character to do so.
- In Metal Slug Attack, he appears as a placement image for the "Event Crank", as of 1.6.0, he's available as a playable unit, with the ability to throw out 3 explosive barrels at a time (at varying distances). Just like Leona and Ralf beforehand, he was a pre-aquisition unit, then was available in the Medal/VIP crank, and in later updates, can now can be bought from the POW Rescue Shop.
- Unlike on main series, Clark doesn't use his "Metal Slug Version" voice in Metal Slug Defense and Attack,instead he uses the "KoF Version" this also happens with Ralf.