If you are looking for a nice, simple app for biographies, you might want to check out People HD. There is nothing flashy about this app, but it does provide short and simply written biographies of over 100 key figures from world history. Personalities as diverse as Joseph Stalin and John Lennon or Stephen Hawking and Confucius are included and all time periods and careers are included as well.
People HD allows students to select an individual and read a short one page biography, see a timeline of their life, and read select quotes from the individual. While this is not a treasure trove of information by any stretch, People HD would serve as a great introduction to some of these personalities, as a lesson supplement, or as a way for students to narrow choices for research topics, or for reading more in-depth biographies of these individuals.
The developers of People HD are always looking including more biographies, so keep an eye out for more updates!
Also of interest:
Portraits HD – From the same developer, this app includes more detailed portraits of the individuals included in the People HD app.