iOS: Whether it's public or private to you, when your data is on your iPhone it's just there for anyone to see. There's no separation and you can't keep your secrets safe without locking the entire thing down with a pin. That's where Ben the Bodyguard can help.
He's an app/cartoon personality that'll hide your secret passwords, photos, reminders and more. What's also really nice is that your private data is protected by a password that can be more complex than a four-digit PIN.
Ben the Bodyguard definitely comes with its (very polished) charm, and that's part of what you're paying for. While there's something to be said for fun, it's a solid app in its functionality, too, so you're not out $5.99 for a graphic novel-esque security app. It stores pretty much any kind of information you'd need in your phone, uses 256-bit encryption to keep it safe, and notifies you discreetly when it needs to. Basically, Ben gives you a private bucket on your iPhone so you don't have to worry about friends, family, or complete strangers learning your secrets.
If $6 is a little too step for you, however, Private Data is a less-flashy but free alternative.