Arsenal, in the English Premier League, just pulled off an undefeated season. Is there any other Professional Sports team that has managed this?
1972 Miami Dolphins in the NFL.
The 1972 Miami Dolphins had a 14-0 mark in the regular season, then won three playoff games to finish 17-0.
St George Rugby League team won every premiership from 1956 until 1966. The 1959 team remained unbeaten throughout the season.