Jonas Mačiulis (born February 10, 1985 in Kaunas, Lithuanian SSR, USSR) is a Lithuanian professional basketball player, currently playing as a small forward for the most successful Lithuanian team Žalgiris and the Lithuania national basketball team. He is 2.00m (6 ft 6 ¾ in) in height. He shares his name with the famous Lithuanian poet Maironis.

He made his debut in the LKAL with Žalgiris-Arvydas Sabonis school (2nd Team of Žalgiris) during the 2002-03 season. For the 2004-05 season signed for by the LKL team Nevėžis and was back to the first Žalgiris team for the 2005-06 season. He has an aggressive playing style and hard nosed defense; also a good rebounder, but needs to improve his passing and dribbling skills, because his future is at 2 position.

Awards and achievements

• Silver medalist World Junior Championship - 2003
• Bronze medalist World Under-20 - 2004
• World Under-21 Champion - 2005
• LKL vicechampion - 2006
• BBL vicechampion - 2006, 2007
• LKF Cup winner - 2007, 2008
• LKL champion - 2007, 2008
• BBL champion - 2008
• 2007 Summer Universiade champion - 2007
• Eurobasket 2007 Bronze medalist - 2007
• Lithuanian fedaration cup Champion - 2008
• Baltic Basketball League champion - 2008
• LKL Champion - 2008