Mass Effect Wiki is great for looking up anything about characters, places and events from the games. But their book and comic summaries are questionable, and the science often inaccurate.
The most reliable source of information is the Codex, which consists of ingame encyclopedic entries.
Mass Effect 1, Mass Effect 2 and Mass Effect 3 as movies. It’s a male Shepard with a different background from what I play and write and possibly very different choices during important missions, but it’s more than illustrative. Probably the best way to learn about ME short of playing the games themselves.
An enlightening interview with the voice actors (especially part 2 and what Fred Tatasciore – who played Saren – has to say about the character).