Pedro Kantor is the current Chapter Master of the Crimson Fists. As of the latest novel (999.m41) that chapter is dangerously under-strength and has to campaign not to be folded into other chapters, though one has to wonder why they're being targeted for this and not some other sons of Dorn. As successors of the Imperial Fists they are experts in being tougher than your average spess mahreen. Known also for surviving the downfall of the Crimson Fists fortress monastery and managing to organize the survivors and take out the orks on Rynn's World, saving little kids and women, and making an Ork Warboss run away from him. These achievements are made all the more impressive by the glorious amount of Derp and FAIL that plagued the chapter's resistance before he took charge.
He is bros for life with fellow crimsoner and the mighty Spaniard himself Alessio Cortez. While currently Cortez is missing, presumed dead, Kantor thinks his bro has merely been kidnapped by the Eldar (although how you kidnap a giant killing machine, especially one as insanely tough as Cortez, is anyone's guess). Pedro would probably get along brilliantly with Ekene Dubaku given their similar workloads and problems.
He also had his fluff messed up by the dark one. In one battle he was killing Orks near Rynn City and was helped by the Eldar. However, when he went to talk to his rescuers, he was told "Thank me not, for the next time we meet on the battlefield it is I who shall bear your blood", but I guess that this was too awesome and grimdark for Matt Ward to handle.
Originally named Pedro Cantor, back in the days of Rogue Trader. Pete Cantor was the play tester he was named after.
On the Tabletop
Pedro Kantor isn't exceptional in any one area, but neither does he lag behind in any area. First off we have his rules, ATSKNF and Chapter Tactics (Imperial Fists), independent character, Hold the Line, and Oath of Rynn. He gives sternguard objective secured and everyone in his detachment gets preferred enemy (Orks). Every friendly model within 12" of him gets an extra attack, giving him great deathstar potential. His warlord trait gives him FNP for a bit of extra durability, which is nice. He comes to the field with artificer armor, an iron halo, frag and krak grenades, an orbital strike beacon, and a relic gun called "Dorn's Arrow" an assault 4 ap4 storm bolter.
Pedro is a solid choice for what he brings, and he opens up a lot of fun tactical options. With the extra wound and FNP he's a bit tougher than most characters, though his lack of Eternal Warrior means you shouldn't be too ballsy with that. Honestly though, Pedro himself is pretty vanilla, it's the tactical options he opens up that you take him for. For example think of Pedro in a full unit of honor guard. You have two attacks base, an extra attack from 2 CCWs, one more attack from their standard, and finally ONE MORE attack from Kantor's buff. You now have, on a charge, fifty nine(!) strength 4 with an extra six power fist attacks for flavor. You can buff this further by buying your guard relic blades and having a command squad nearby, adding +1 A and S, bringing you to a grand total of SIXTY NINE STRENGTH 5 AP3 ATTACKS on the charge, in case you need to kill an entire company of space marines in melee for some reason. Of course this squad is going to cost you just shy of 1000 points and it's one of the biggest fire magnets in the game, but it could be fun! If you're looking for something mildly less cheesy you can make an unbound list of sternguard with lots of combigravs and meltas. They have objective secured, so this can work quite well.