It looks like the last one gets to Woodward & Daines at 2:04 AM on a weekday. It leaves Woodward & Congress in downtown Detroit at 1:15 AM.

Saturdays, the last bus leaves Woodward & Congress at 12 midnight exactly, and gets to Woodward & Daines at 12:59 AM. Sundays, it leaves at 12:05 AM, and gets to Woodward & Daines a little more quickly, arriving at 12:52 AM. Take that with a grain of salt, though, as a lot of people complain bitterly about the bus schedule being somewhat unreliable.

The link I am using is here: http://www.smartbus.org/Smart/Ride%2.../Route1qr.aspx
I found that I had to highlight the top row of the schedule, which shows the stations, by clicking and draging my mouse across the entire top row. That could be attributable to my using Firefox on their kludgy site [[which it is).

What possesses me to post this at midnight when I'm supposed to be packing my bags, I'll never know.