Assuming you mean on iOS, there is a Final Fantasy Tactics game and one called Song Summoner for starters. Of course, being Square games, they are both pretty pricey, but there is a lite version of Song Summoner for you to try out. There is also one called Kingturn RPG that is free with a $5 full version unlock.
Turn-based, SRPG? I remember only a few good ones... Warhammer Quest XCom Skulls of the Shogun Partia War of Eustrath Hunters 2 Tactical Soldier Undead Rising
While that is a good game, if someone asked for games similar to Disgaea, that would probably not be on my list of suggestions.
Don't know Disgaea, but if you want something with a touch of old-school, I highly recommend the Kingturn series. For even more old-school feeling, take a look at The Quest, quite extensive series by now. The Spiderweb games (Avadon, Avernum series) of course. They all have interesting stories and settings. Ash and Ash2. But I'm a bit reluctant with those, as they never got all the announced chapters. Ravenmark of course, for more of a Strategy game. And King of Dragon Pass for a truly unique and special experience. Not sure if this interests you, as it's boardgame-style: Elder Sign:Omens. Cthulhu fhtagn! All of the above have fantasy settings, by the way.
Good start! Aliens vs Humans ArmA Tactics Avadon Avernum: The Pitt Avernum 6 Battle Dungeon Risen Battle for Wesnoth [HD available] Baldur's Gate Enhanced Edition 1&2 Blazing Souls Accelate Breach & Clear Call of Cthulhu: The Wasted Land Cheap Tactics Dark Quest Death Tower Dungeon Lore [iPad only] Fatal League Final Fantasy Tactics: The War of Lions Frontline Tactics Frozen Synapse Greed Corp Hero Mages Heroes of Steel Highborn Hunters: Episode 1 Hunters 2 iWesnoth Keg Bearer [iPad] Kirin Wars Kingturn Kingturn Plus Kingturn Underworld Knighturn Line of Defense Tactics LostStar Tactics Magisteria Mecho Wars Metal Brigade Tactics [iPad] Mighty Dungeons Mysterious Castle The Pantheon Cycle: Shrouded Aspect Partia: The Broken Lineage Perilar Ravenmark: Scourge Estellion Rebirth of Fortune Shadowrun Solarian Tactics Spectrum Souls Sword & Earrings (Sw&Ear) Tactical Warrior Tactical Soldier: Undead Rising Time of Heroes Trouble in Tin Town Uniwar War of Eustrath War of Genesis 3 Episode 1 Warhammer Quest War of Kingdom World to Conquer XCOM: Enemy Unknown Specifically more like disagea if looking for that Japanese/anime vibe: Spectrum Souls Blazing Souls Accelate Kingturn series Partia: the Broken Lineage Final Fantasy Tactics: The War of the Lion Rebirth of Fortune
Don't know how I missed that! Added! It was on there but I think I edited it off by accident when I originally posted thinking I had double entered it on the list...