Ballot Box With Check
HTML Entity Browser Test:

U+2611 is the Unicode hex value of the character Ballot Box With Check, which is categorized as "other symbol" in the Unicode 6.0 character table.

Unicode Character Information
Unicode Hex U+2611
General Category Other Symbol [Code: So]
Canonical Combining Class 0
Bidirectional Category ON
Mirrored N
Unicode Character Encodings
Ballot Box With Check HTML Entity ☑ (decimal entity), ☑ (hex entity)
Windows Key Code Alt 9745 or Alt +26111
Programming Source Code Encodings Python hex: u"\u2611", Hex for C++ and Java: "\u2611"
UTF-8 Hexadecimal Encoding 0xE29891
1 To type a Unicode symbol in Windows, hold down the ALT key and enter the decimal or hexadecimal code provided using the numeric keypad. The decimal alt code (Alt 9745) will only work on computers with support for this Unicode character in the active code page. The hexadecimal alt code (Alt +2611) will work for all Unicode characters provided Hex input from the numeric keypad is enabled.
* If the Ballot Box With Check character does not display correctly in your browser, you may not have a Unicode font on your system that supports this particular symbol.