Boris Becker won the 1985 Championships at his first attempt aged 17. He successfully defended his title in 1986. Since then:
!987 Pat Cash won. He had lost in the quarter-finals to Henri Leconte the previous year.
1988 Stefan Edberg won..He lost to in the semi-finals to Ivan Lendl the previous year.
1989-90 saw Becker win again.
1991 –Michael Stich won. He lost in 3rd round to Guy Forget the previous year.
1992 – Andre Agassi won. He lost in the quarter finals to David Wheaton the previous year.
1993 – Pete Sampras won. He lost the in the semi-finals to Goran Ivanisevic the previous year.
1994-95 Pete Sampras again.
1996 – Richard Krajicek won. He in the first round in 1994 to Darren Cahill.
1997-2000 – Pete Sampras again.
2001- Goran Ivanivesic won (see 1993).
2002 – Lleyton Hewitt won. He lost in the first round to Jan-Maichael Gambill in 2000.
2003 – Roger Federer won. He lost in the first round to Mario Ancic the previous year.
2004-09 – Roger Federer again.
2010 – Rafael Nadal. He lost the previous year in the final to Rogere Federer.
In each case I have only shown the most recent loss before their triumph. Most of the players mentioned had taken part in the tournament prior to that.
The question was who was "...the last person to have won a Men's single title at Wimbledon at his first attempt."
Boris did so. Those who have won the tournament since had all failed at earlier attempts (and so did not win it at their first attempt) thus making Boris the last person to win at his first attempt. I was providing some extra information to support that fact.
Thanks Craft 1948 and New Judge. I knew that Boris had won Wimbledon when he was 17 the first unseeded winner, but I'll google harder to verify that he hadn't had a try previously.