People Behind Debian: Steve McIntyre
Steve McIntyre has been contributing to Debian since 1996, 2 years before I joined! But I quickly stumbled upon Steve: in 1999, he was struggling with getting his debian-cd script to produce 2 ISO images (it was the first time that Debian did no longer fit on a single CD), I helped him by rewriting debian-cd with a robust system to split packages on as many ISO images as required.
I remember those times very well because Steve was very supportive of my efforts and it was a real pleasure to get this done. His friendly nature probably also explains why he got elected Debian Project Leader twice!